WO2020217511A1 - Polarizing plate - Google Patents

Polarizing plate Download PDF

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Publication number
WO2020217511A1
WO2020217511A1 PCT/JP2019/018115 JP2019018115W WO2020217511A1 WO 2020217511 A1 WO2020217511 A1 WO 2020217511A1 JP 2019018115 W JP2019018115 W JP 2019018115W WO 2020217511 A1 WO2020217511 A1 WO 2020217511A1
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WO
WIPO (PCT)
Prior art keywords
protective film
rubber particles
mass
meth
film
Prior art date
Application number
PCT/JP2019/018115
Other languages
French (fr)
Japanese (ja)
Inventor
栞 佐藤
崇 南條
Original Assignee
コニカミノルタ株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by コニカミノルタ株式会社 filed Critical コニカミノルタ株式会社
Priority to KR1020217034111A priority Critical patent/KR20210143842A/en
Priority to PCT/JP2019/018115 priority patent/WO2020217511A1/en
Priority to JP2021515735A priority patent/JP7367756B2/en
Priority to TW109108725A priority patent/TWI733376B/en
Publication of WO2020217511A1 publication Critical patent/WO2020217511A1/en

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
    • G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
    • B32B27/308—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers comprising acrylic (co)polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/02—Physical, chemical or physicochemical properties
    • B32B7/023—Optical properties
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/20—Adhesives in the form of films or foils characterised by their carriers
    • C09J7/29—Laminated material
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
    • G02B1/14—Protective coatings, e.g. hard coatings
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2270/00—Resin or rubber layer containing a blend of at least two different polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/40—Properties of the layers or laminate having particular optical properties
    • B32B2307/42—Polarizing, birefringent, filtering

Definitions

  • the present invention relates to a polarizing plate.
  • a polarizing plate used in a display device such as a liquid crystal display device includes a polarizing element and protective films arranged on both sides thereof.
  • a film containing a (meth) acrylic resin such as polymethylmethacrylate as a main component is used because it has excellent transparency, dimensional stability, and low hygroscopicity.
  • the (meth) acrylic resin film is brittle, elastic particles such as rubber particles are further added and used in order to eliminate the brittleness.
  • a polarizing plate using such a (meth) acrylic resin film includes a polarizing element and two protective films arranged on both sides thereof, and the two protective films are polymethylmethacrylate containing elastic particles.
  • a polarizing plate which is a co-extruded film having a core layer of the above and two skin layers of two polymethylmethacrylates which do not contain elastic particles arranged on both sides thereof (for example, Patent Document 1). The same film is used as the two protective films.
  • Such a polarizing plate is punched into a predetermined size and shape according to the product when manufacturing a display device which is a product.
  • a display device having a polarizing plate having reduced interlayer adhesion is likely to cause display unevenness due to keystrokes when used for a long time in a high humidity environment.
  • the present invention has been made in view of the above circumstances, and provides a polarizing plate capable of suppressing cracks and delamination during punching and reducing display unevenness due to keystrokes when used for a long time in a high humidity environment.
  • the purpose is.
  • the polarizing plate of the present invention comprises a polarizer, a protective film A arranged on one surface of the polarizer, a protective film B arranged on the other surface of the polarizer, and the polarization of the protective film B.
  • the average aspect ratio of the rubber particles a is 1.0 to 1.1 in a cross section along the thickness direction of the protective film A, which contains the (meth) acrylic resin and the rubber particles b, and the protection.
  • the average aspect ratio of the rubber particles b is 1.2 to 3.0
  • the (meth) acrylic resin contained in the protective film B is the (meth) acrylic resin.
  • the acrylic resin 50 to 95% by mass of the structural unit derived from methyl methacrylate, 1 to 25% by mass of the structural unit derived from phenylmaleimide, and 1 to 25% by mass of the structural unit. It is a copolymer containing a structural unit derived from the acrylic acid alkyl ester of.
  • a polarizing plate capable of suppressing cracks and delamination during punching and reducing display unevenness due to keystrokes when used for a long time in a high humidity environment.
  • FIG. 1 is a cross-sectional view showing a polarizing plate according to an embodiment of the present invention.
  • FIG. 2 is a cross-sectional view illustrating an estimation mechanism in the punching process of the polarizing plate.
  • 3A and 3B are diagrams showing a punching step of a polarizing plate in an example.
  • FIG. 1 is a cross-sectional view showing a polarizing plate 100 according to the present embodiment.
  • the polarizing plate 100 is a protective film 120A arranged on a polarizing element 110 (polarizer) and one surface thereof and containing rubber particles 150a (rubber particles a). (Protective film A), a protective film 120B (protective film B) arranged on the other surface and containing rubber particles 150b (rubber particles b), and an adhesion arranged between the protective film 120A and the polarizer 110. It has an agent layer 130A (adhesive layer A) and an adhesive layer 130B (adhesive layer B) arranged between the protective film 120B and the polarizer 110.
  • the polarizing plate 100 further has an adhesive layer 140 arranged on the surface of the protective film 120B opposite to the polarizer 110.
  • the pressure-sensitive adhesive layer 140 is a layer for attaching the polarizing plate 100 to a display element (not shown) such as a liquid crystal cell.
  • the surface of the pressure-sensitive adhesive layer 140 is usually protected by a release film (not shown).
  • the present inventors speculated as follows about the mechanism by which cracks and delamination occur in the punching process of the polarizing plate.
  • FIG. 2 is a cross-sectional view illustrating an estimation mechanism in the punching process of the polarizing plate 100.
  • FIG. 2A is a cross-sectional view when the blade 160 is pushed into the polarizing plate 100
  • FIG. 2B is a cross-sectional view when the blade 160 is pulled out from the polarizing plate 100.
  • the protective film 120A does not push the adjacent layer due to the pushing of the blade 160, so that the stress generated by the pushing of the blade is Although small (dotted arrow in FIG. 2A); the protective film 120B is pushed by the blade because the adjacent layers (adhesive layer 130B, polarizer 110, adhesive layer 130A and protective film 120A) are pushed by the blade.
  • the generated stress tends to increase (solid line arrow in FIG. 2A).
  • the protective film 120B is more physically deformed by pushing the blade than the protective film 120A, and is more likely to occur in a wide range.
  • cracks are likely to occur in the protective film 120B when the blade 160 is pushed in, and delamination is likely to occur between the protective film 120B and the adhesive layer 130B when the blade 160 is pulled out.
  • the present inventors have the average aspect ratio of the rubber particles contained in the protective film arranged on one surface of the polarizer and the arrangement on the other surface of the polarizer. Rather than making the average aspect ratio of the rubber particles contained in the protective film the same; the average aspect ratio of the rubber particles 150b contained in the protective film 120B is larger than the average aspect ratio of the rubber particles 150a contained in the protective film 120A. It was found that cracks and delamination can be suppressed by increasing the height (see FIG. 2A).
  • the average aspect ratio of the rubber particles 150b contained in the protective film 120B is adjusted to 1.2 to 3.0.
  • the rubber particles 150b contained in the protective film 120B can satisfactorily follow the deformation of the protective film 120B caused by the pushing of the blade 160, so that the stress can be relaxed and cracks and the like can be less likely to occur. ..
  • the hardness of the rubber particles 150b is relatively high (the amount of styrene is relatively large) and the hardness of the rubber particles 150b (the amount of styrene)> the hardness of the rubber particles 150a (the amount of styrene)
  • the effect of setting the average aspect ratio within the above range is further obtained. Easy to get rid of. Further, in the protective film 120B, since the stress generated when the blade is pushed in can be reduced, delamination between the protective film 120B and the adhesive layer 130B can be less likely to occur when the pushed blade is pulled out (see FIG. 2B).
  • the present inventors have described the (meth) acrylic resin contained in the protective film 120B as a structural unit (U1) derived from methyl methacrylate, a structural unit (U2) derived from phenylmaleimide, and an alkyl acrylate. It has been found that by using a copolymer containing a structural unit (U3) derived from an ester in a predetermined ratio, delamination when the blade 160 is pulled out can be further suppressed without deteriorating brittleness (Fig.). See 2B).
  • the structural unit (U2) derived from phenylmaleimide has high flatness and has an appropriate polarity, so that the average aspect ratio is moderately high and the affinity with the flat rubber particles 150b tends to increase. As a result, interfacial delamination with the rubber particles 150b can be suppressed, and thereby delamination between the protective film 120B and the adhesive layer 130B can be suppressed.
  • Polarizer A polarizing element is an element that allows only light on a plane of polarization in a certain direction to pass through.
  • the polarizer can usually be a polyvinyl alcohol-based polarizing film.
  • Examples of the polyvinyl alcohol-based polarizing film include a polyvinyl alcohol-based film dyed with iodine and a film dyed with a dichroic dye.
  • the polyvinyl alcohol-based polarizing film may be a film obtained by uniaxially stretching a polyvinyl alcohol-based film and then dyeing it with iodine or a bicolor dye (preferably a film further subjected to a durability treatment with a boron compound); polyvinyl.
  • An alcohol-based film may be a film that has been dyed with iodine or a bicolor dye and then uniaxially stretched (preferably a film that has been further subjected to a durability treatment with a boron compound).
  • the absorption axis of the polarizer 110 is usually parallel to the maximum stretching direction.
  • Examples of the polyvinyl alcohol-based polarizing film include the ethylene unit content of 1 to 4 mol%, the degree of polymerization of 2000 to 4000, and the degree of saponification of 99, which are described in JP-A-2003-248123 and JP-A-2003-342322. 0-99.99 mol% ethylene-modified polyvinyl alcohol is used.
  • the thickness of the polarizer is preferably 5 to 30 ⁇ m, and more preferably 5 to 20 ⁇ m from the viewpoint of thinning the polarizing plate.
  • the protective film A contains a (meth) acrylic resin and rubber particles a.
  • the (meth) acrylic resin contained in the protective film A may be a copolymer containing a structural unit derived from methyl methacrylate, or may be a copolymer containing a structural unit derived from methyl methacrylate and a structural unit derived from methyl methacrylate. It may be a copolymer containing a structural unit derived from a copolymerizable monomer other than methyl methacrylate which can be copolymerized with the copolymer.
  • the copolymerization monomer is not particularly limited, and the alkyl group other than methyl methacrylate, such as ethyl (meth) acrylate, propyl (meth) acrylate, and six-membered ring lactone (meth) acrylic acid ester, has 1 to 1 to carbon atoms.
  • (meth) acrylic acid esters ⁇ , ⁇ -unsaturated acids such as (meth) acrylic acid; unsaturated group-containing divalent carboxylic acids such as maleic anhydride, fumaric acid, itaconic acid; styrene, ⁇ -methylstyrene Aromatic vinyls such as; ⁇ , ⁇ -unsaturated nitriles such as acrylonitrile and methacrylonitrile; maleimides such as maleimide and N-substituted maleimide; maleic anhydride and glutaric anhydride are included.
  • One type of copolymerization monomer may be used, or two or more types may be used in combination.
  • a homopolymer containing a structural unit derived from methyl methacrylate (polymethyl methacrylate) or a structural unit derived from methyl methacrylate and glutal a homopolymer containing a structural unit derived from methyl methacrylate (polymethyl methacrylate) or a structural unit derived from methyl methacrylate and glutal.
  • An imide structural unit for example, a structural unit derived from (meth) acrylic acid ester reacted with an imidizing agent such as amine), a structural unit derived from glutaric anhydride, or a six-membered ring lactone (meth).
  • It is preferably a copolymer containing a structural unit derived from an acrylic acid ester (lactone ring structural unit), and more preferably a homopolymer containing a structural unit derived from methyl methacrylate (polymethylmethacrylate).
  • the content of the structural unit derived from methyl methacrylate is preferably 80 to 100% by mass, more preferably 90 to 100% by mass, based on all the structural units constituting the (meth) acrylic resin. ..
  • the type and composition of the (meth) acrylic resin monomer can be specified by 1 1 H-NMR.
  • the glass transition temperature (Tg) of the (meth) acrylic resin is preferably 90 ° C. or higher, more preferably 100 to 150 ° C.
  • the protective film A in which the Tg of the (meth) acrylic resin is 90 ° C. or higher can have good heat resistance.
  • the glass transition temperature (Tg) of the (meth) acrylic resin can be measured using DSC (Differential Scanning Colory) according to JIS K7121-2012 or ASTM D3418-82. ..
  • the weight average molecular weight (Mw) of the (meth) acrylic resin is not particularly limited and can be appropriately set according to the film forming method.
  • the weight average molecular weight of the (meth) acrylic resin is preferably 100,000 to 300,000.
  • the weight average molecular weight of the (meth) acrylic resin is preferably 500,000 to 3,000,000, more preferably 600,000 to 2,000,000. ..
  • the weight average molecular weight of the (meth) acrylic resin is in the above range, sufficient mechanical strength (toughness) can be imparted to the film without impairing the film-forming property.
  • the weight average molecular weight (Mw) of the (meth) acrylic resin can be measured in terms of polystyrene by gel permeation chromatography (GPC). Specifically, the measurement can be performed using a Tosoh company HLC8220GPC) and a column (Tosoh company TSK-GEL G6000HXL-G5000HXL-G5000HXL-G4000HXL-G3000HXL series). The measurement conditions may be the same as in the examples described later.
  • the content of the (meth) acrylic resin is preferably 60% by mass or more, and more preferably 70% by mass or more with respect to the protective film A.
  • Rubber particles a The rubber particles a contained in the protective film A can impart toughness and flexibility to the protective film A.
  • the average aspect ratio of the rubber particles a is preferably 1.0 to 1.1 in the cross section of the protective film A along the thickness direction.
  • the stress generated in the protective film A by pushing the blade is smaller than the stress generated in the protective film B by pushing the blade. Therefore, it is necessary to adjust the followability of the rubber particles a as much as the rubber particles b. Because there isn't. Further, when the blade is pushed into the protective film A, the stress is likely to be applied isotropically to the rubber particles 150a, so that the stress is easily dissipated by the rubber particles 150a itself.
  • the average aspect ratio means the average value of the aspect ratios of the plurality of rubber particles a.
  • the aspect ratio means the ratio (major axis / minor axis) of the major axis of the rubber particles to the minor axis.
  • the major axis of the rubber particles a can be measured as the length in the longitudinal direction (the length of the long side) of the rectangle circumscribing the rubber particles a;
  • the minor axis can be measured as the length (the length of the short side) of the rectangle circumscribing the rubber particles a in the lateral direction.
  • the cross section along the thickness direction of the protective film A specifically refers to a cross section along the thickness direction of the protective film A that is parallel to the in-plane slow phase axis.
  • the in-plane slow-phase axis refers to the axis having the maximum refractive index on the film surface.
  • the in-plane slow-phase axis of the protective film A cannot be specified, it means a cross section parallel to the width direction (TD direction) of the protective film A among the cross sections along the thickness direction of the protective film A.
  • the average major axis of the rubber particles a is preferably 100 to 400 nm. When the average major axis of the rubber particles a is 100 nm or more, sufficient toughness is easily imparted to the film, and when it is 400 nm or less, the transparency of the film is unlikely to decrease.
  • the average major axis of the rubber particles a is more preferably 150 to 300 nm.
  • the average major axis of the rubber particles is the average value of the major axis of the rubber particles.
  • the average aspect ratio and the average major axis of the rubber particles a can be calculated by the following methods.
  • the observation region may be a region corresponding to the thickness of the protective film A, or a region of 5 ⁇ m ⁇ 5 ⁇ m.
  • the number of measurement points may be one.
  • the area of 5 ⁇ m ⁇ 5 ⁇ m is used as the observation area, the number of measurement points may be four.
  • the average value of the aspect ratios obtained from the plurality of rubber particles is defined as the "average aspect ratio”
  • the average value of the major axes obtained from the plurality of rubber particles is defined as the "average major axis”.
  • the average aspect ratio and average major axis of the rubber particles a can be adjusted according to the film forming conditions and stretching conditions of the protective film A. In order to reduce the average aspect ratio of the rubber particles a, for example, it is preferable to reduce the stretching ratio of the protective film during film formation (preferably unstretched).
  • Such rubber particles a are particles containing a rubber-like polymer (crosslinked polymer).
  • rubber-like polymers include butadiene-based crosslinked polymers, (meth) acrylic-based crosslinked polymers, and organosiloxane-based crosslinked polymers.
  • the (meth) acrylic crosslinked polymer is preferable, and the acrylic crosslinked polymer (acrylic rubber-like polymer) is preferable from the viewpoint that the difference in refractive index from the methacrylic resin is small and the transparency of the protective film is not easily impaired. More preferred.
  • the rubber particles are preferably particles containing the acrylic rubber-like polymer (a1).
  • the acrylic rubber-like polymer (a1) is a crosslinked polymer containing an acrylic acid ester as a main component. That is, the acrylic rubber-like polymer (a1) has a structural unit derived from an acrylic acid ester, a structural unit derived from a monomer copolymerizable therewith, and two or more radically polymerizable groups (non-conjugated) in one molecule. It is preferably a crosslinked polymer containing a structural unit derived from a polyfunctional monomer having a reactive double bond.
  • the acrylic acid ester is preferably an acrylic acid alkyl ester having 1 to 12 carbon atoms of an alkyl group such as methyl acrylate and butyl acrylate.
  • the acrylic ester may be one kind or two or more kinds. From the viewpoint of lowering the glass transition temperature of the rubber particles to ⁇ 15 ° C. or lower, the acrylic acid ester preferably contains at least an acrylic acid alkyl ester having 4 to 10 carbon atoms.
  • the content of the structural unit derived from the acrylic acid ester is preferably 40 to 80% by mass, preferably 45 to 65% by mass, based on all the structural units constituting the acrylic rubber-like polymer (a). Is more preferable. When the content of the acrylic acid ester is 45% by weight or more, it is easy to impart sufficient toughness to the film.
  • the copolymerizable monomer is a monomer copolymerizable with the acrylic acid ester other than the polyfunctional monomer. That is, the copolymerizable monomer does not have two or more radically polymerizable groups.
  • copolymerizable monomers include methacrylic acid esters such as methyl methacrylate; styrenes such as styrene and methylstyrene; unsaturated nitriles such as acrylonitrile and methacrylonitrile.
  • the copolymerizable monomer preferably contains styrenes.
  • the content of the structural unit derived from the styrenes of the rubber particles a contained in the protective film A is the structure derived from the styrenes of the rubber particles b contained in the protective film B. It is preferably less than the content of the unit. That is, the content of the structural unit derived from the styrenes of the acrylic rubber-like polymer (a1) is preferably smaller than the content of the structural unit derived from the styrenes of the acrylic rubber-like polymer (b1). ..
  • the content of the structural unit derived from the styrenes of the acrylic rubber-like polymer (a1) is 5 to 55% by mass with respect to all the structural units constituting the acrylic rubber-like polymer (a1). It is preferably, and more preferably 30 to 50% by mass.
  • the content of the structural unit derived from styrenes is within the above range, the rubber particles a can be easily adjusted to an appropriate hardness.
  • the content of the structural unit derived from styrenes of the rubber particles can be measured from the area ratio of the peak detected by the thermal decomposition GC / MS. Specifically, it can be measured by the following procedure. 1) First, some known samples having different styrene contents are prepared, pyrolysis GC / MS measurement is performed, and a calibration curve is prepared based on the obtained peak area ratio. 2) Next, pyrolysis GC / MS measurement is performed on the sample to be measured, and the peak area ratio is calculated. 3) The peak area ratio obtained in 2) above is collated with the calibration curve in 1) above to specify the content of styrenes in the sample to be measured.
  • the measurement conditions for GCMS can be as follows.
  • Measuring device SHIMAZU GCMS QP2010 Column type: Ultra Alloy-5 (size 30 m x diameter 0.25 mm) Carrier gas type: He Flow rate condition: 1.8 mL / min Column oven temperature condition: 40 ° C-10 ° C / min-320 ° C Interface temperature: 300 ° C Ion source temperature: 200 ° C Detection mode: SIM (target ion: m / z104, confirmed ion: m / z78)
  • polyfunctional monomers examples include allyl (meth) acrylate, triallyl cyanurate, triallyl isocyanurate, diallyl phthalate, diallyl malate, divinyl adipate, divinylbenzene, ethylene glycol di (meth) acrylate, and diethylene glycol (meth).
  • acrylates triethylene glycol di (meth) acrylates, trimethyl roll propanthry (meth) acrylates, tetromethylol methanetetra (meth) acrylates, dipropylene glycol di (meth) acrylates, and polyethylene glycol di (meth) acrylates.
  • the content of the structural unit derived from the polyfunctional monomer is preferably 0.05 to 10% by mass, preferably 0.1 to 5% by mass, based on all the structural units constituting the acrylic rubber-like polymer (a1). More preferably, it is by mass%.
  • the content of the polyfunctional monomer is 0.05% by mass or more, the degree of cross-linking of the obtained acrylic rubber-like polymer (a) is easily increased, so that the hardness and rigidity of the obtained film are not excessively impaired.
  • it is 10% by mass or less the toughness of the film is not easily impaired.
  • the particles containing the acrylic rubber-like polymer (a1) may be particles made of the acrylic rubber-like polymer (a1); in the presence of the acrylic rubber-like polymer (a1), a methacrylic acid ester.
  • the core portion constituting the core-shell type particles contains an acrylic rubber-like polymer (a1).
  • the shell portion constituting the core-shell type particles contains a polymer (a2) (graft component) containing a structural unit derived from a methacrylic acid ester.
  • the methacrylic acid ester is preferably an alkyl methacrylate ester having 1 to 12 carbon atoms of an alkyl group such as methyl methacrylate.
  • the methacrylic acid ester may be one kind or two or more kinds.
  • the content of the methacrylic acid ester is preferably 50% by mass or more with respect to all the structural units constituting the polymer (a2).
  • the content of the methacrylic acid ester is 50% by mass or more, it is possible to make it difficult to reduce the hardness and rigidity of the obtained film.
  • the content of the methacrylic acid ester is more preferably 70% by mass or more with respect to all the structural units constituting the polymer.
  • the polymer (a2) may further contain structural units derived from other copolymerizable monomers.
  • examples of other monomers are acrylic acid esters such as methyl acrylate, ethyl acrylate, n-butyl acrylate; benzyl (meth) acrylate, dicyclopentanyl (meth) acrylate, phenoxy (meth) acrylate.
  • the weight ratio (graft ratio) of the graft component in the rubber particles is preferably 10 to 250%, more preferably 25 to 200%, more preferably 40 to 200%, and 60 to 150%. Is more preferable.
  • the mass ratio is 10% or more, the proportion of the shell portion is not too small, so that the hardness and rigidity of the film are not easily impaired.
  • the mass ratio is 250% or less, the proportion of the core portion is not too small, so that the toughness and brittleness improving effect of the film are not easily impaired.
  • the glass transition temperature (Tg) of the rubber particles can be room temperature or lower (25 ° C. or lower). Further, the glass transition temperature of the rubber particles a is preferably lower than the glass transition temperature of the rubber particles b. When the glass transition temperature (Tg) of the rubber particles satisfies the above range, it is easy to impart sufficient toughness to the film.
  • the glass transition temperature (Tg) of the rubber particles is measured by the same method as described above.
  • the glass transition temperature (Tg) of the rubber particles a can be adjusted, for example, by adjusting the composition and graft ratio of the polymers constituting the core portion and the shell portion.
  • Tg glass transition temperature
  • the content of the rubber particles a in the protective film A is not particularly limited, but is preferably higher than the content of the rubber particles b in the protective film B. Specifically, the content of the rubber particles a in the protective film A is preferably 12 to 25% by mass, more preferably 15 to 22% by mass with respect to the protective film A. When the content of the rubber particles is 12% by mass or more, it is easy to impart sufficient toughness or flexibility to the protective film A, and when it is 25% by mass or less, it is easy to suppress an increase in internal haze.
  • the protective film A may further contain components other than the above, if necessary.
  • examples of other ingredients include matting agents and the like.
  • examples of the matting agent include inorganic fine particles such as silica particles and organic fine particles having a glass transition temperature of 80 ° C. or higher.
  • the tensile elastic modulus of the protective film A is not particularly limited, but is preferably lower than the tensile elastic modulus of the protective film B from the viewpoint of facilitating suppression of cracks and delamination when punching the polarizing plate.
  • the stress generated in the protective film A by pushing the blade is smaller than the stress generated in the protective film B. Therefore, the load applied to the rubber particles a of the protective film A can be adjusted by adjusting the protective film. This is because it is not as necessary as B.
  • the tensile elastic modulus of the protective film A is relatively low, it is possible to reduce the "stress caused by the tip of the blade” and the "stress generated by pushing the protective film A" received by the protective film B.
  • the tensile elastic modulus of the protective film A at 25 ° C. is preferably 1.6 to 2.6 GPa.
  • the tensile elastic modulus of the protective film A can be measured according to JIS K7127. Specifically, it can be measured by the following procedure. 1) The protective film A is cut into 1 cm (TD direction) ⁇ 10 cm (MD direction) to prepare a sample piece, and the humidity is adjusted for 24 hours in an environment of 25 ° C. and 60% RH. 2) The tensile elasticity of the obtained sample piece is measured by the tensile test method described in JIS K7127.
  • the sample piece is set in the Tensilon manufactured by Orientec Co., Ltd., and the tensile elastic modulus is measured when the tensile test is performed under the conditions of a distance between chucks of 50.0 mm and a tensile speed of 50 mm / min. The measurement is performed at 25 ° C. and 60% RH.
  • the tensile elastic modulus of the protective film A can be adjusted by the composition of the (meth) acrylic resin, the content and composition of the rubber particles a, and the like. From the viewpoint of lowering the tensile elastic modulus of the protective film A, the ratio of structural units derived from the ring-containing monomer of the (meth) acrylic resin may be lowered, the content of the rubber particles a may be increased, or the styrene of the rubber particles a may be increased. It is preferable to reduce the content of structural units derived from the class.
  • the protective film A preferably has high transparency.
  • the haze of the protective film A is preferably 2.0% or less, and more preferably 1.0% or less. Haze can be measured in accordance with JIS K-6714 with a haze meter (HGM-2DP, Suga Test Instruments) at 25 ° C. and 60% RH for a sample of 40 mm ⁇ 80 nm.
  • the thickness of the protective film A is not particularly limited, but is preferably thicker than the thickness of the protective film B.
  • the rigidity of the protective film A is increased. Therefore, in the punching process of the polarizing plate, it is easy to reduce the deformation of not only the protective film A but also the entire polarizing plate when the blade is punched. ..
  • the thickness of the protective film A is preferably 40 to 100 ⁇ m, more preferably 50 to 80 ⁇ m.
  • the protective film B can function as a retardation film arranged between a polarizing element and a display element such as a liquid crystal cell when used as a display device.
  • the protective film B contains a (meth) acrylic resin and rubber particles b.
  • the (meth) acrylic resin contained in the protective film B is composed of a structural unit (U1) derived from methyl methacrylate, a structural unit (U2) derived from phenylmaleimide, and an acrylic acid alkyl ester. It is a copolymer containing the derived structural unit (U3).
  • the content of the structural unit (U1) derived from methyl methacrylate is preferably 50 to 95% by mass, preferably 70 to 90% by mass, based on all the structural units constituting the (meth) acrylic resin. Is more preferable.
  • the structural unit (U2) derived from phenylmaleimide has a structure with high flatness and has an appropriate polarity. As a result, it is easy to suppress the formation of voids between the rubber particles and the resin due to the interaction between the structure and the rubber particles against the deformation in the film surface that occurs during punching. As a result, it is easy to suppress the interfacial delamination between the (meth) acrylic resin and the rubber particles, and thereby the delamination between the protective film B and the adhesive layer can also be suppressed.
  • the content of the structural unit (U2) derived from phenylmaleimide is preferably 1 to 25% by mass with respect to all the structural units constituting the (meth) acrylic resin.
  • the content of the structural unit (U2) derived from phenylmaleimide is 1% by mass or more, it is easy to suppress the interfacial peeling between the rubber particles b and the (meth) acrylic resin, whereby the protective film B and the adhesive It is easy to suppress delamination with the layer.
  • the content of the structural unit (U2) derived from phenylmaleimide is 25% by mass or less, the brittleness of the protective film B is not easily impaired.
  • the content of the structural unit (U2) derived from phenylmaleimide is more preferably 7 to 15% by mass.
  • the structural unit (U3) derived from the acrylic acid alkyl ester can suppress the interfacial peeling between the (meth) acrylic resin and the rubber particles b.
  • the polymer (b2) constituting the shell portion of the rubber particles b has a structural unit derived from an acrylic acid ester such as butyl acrylate, as will be described later, a structural unit derived from the acrylic acid alkyl ester. Since (U3) has a high affinity with the structural unit derived from the acrylic acid ester, the affinity between the (meth) acrylic resin and the rubber particles b can be enhanced.
  • the acrylic acid alkyl ester is preferably an acrylic acid alkyl ester having an alkyl moiety having 1 to 7 carbon atoms, preferably 1 to 5 carbon atoms.
  • alkyl acrylates include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-hydroxyethyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate and the like.
  • the content of the structural unit (U3) derived from the acrylic acid alkyl ester is preferably 1 to 25% by mass with respect to all the structural units constituting the (meth) acrylic resin.
  • the content of the structural unit (U3) derived from the acrylic acid alkyl ester is 1% by mass or more, it is easy to suppress the interfacial peeling between the (meth) acrylic resin and the rubber particles, and when it is 25% by mass or less, Heat resistance is not easily impaired.
  • the content of the structural unit derived from the acrylic acid alkyl ester is more preferably 5 to 15% by mass.
  • the ratio of the structural unit (U2) derived from phenylmaleimide to the total amount of the structural unit (U2) derived from phenylmaleimide and the structural unit (U3) derived from the acrylic acid alkyl ester shall be 20 to 70% by mass. Is preferable. When the ratio is 20% by mass or more, the heat resistance and tensile elastic modulus of the protective film B are appropriately increased, and the interfacial peeling between the rubber particles b and the resin and the delamination between the protective film B and the adhesive layer are caused. When it is 70% by mass or less, the protective film B does not become too brittle.
  • the (meth) acrylic resin may further contain structural units derived from monomers other than the above, if necessary.
  • Examples of such other monomers include those similar to those listed as the copolymerization monomers constituting the (meth) acrylic resin used in the protective film A.
  • the glass transition temperature (Tg) of the (meth) acrylic resin is preferably 105 ° C. or higher, more preferably 110 to 150 ° C.
  • Tg of the (meth) acrylic resin is within the above range, not only the heat resistance of the protective film B can be easily increased, but also the drying efficiency during cast film formation can be easily increased.
  • the weight average molecular weight (Mw) of the (meth) acrylic resin is preferably 500,000 to 3,000,000.
  • the weight average molecular weight of the (meth) acrylic resin is in the above range, sufficient mechanical strength (toughness) can be imparted to the film.
  • the weight average molecular weight of the (meth) acrylic resin is more preferably 600,000 to 2,000,000.
  • the content of the (meth) acrylic resin is preferably 60% by mass or more, and more preferably 70% by mass or more with respect to the protective film B.
  • Rubber particles b The rubber particles b contained in the protective film B can impart toughness to the protective film B in the same manner as described above.
  • the average aspect ratio of the rubber particles b is preferably 1.2 to 3.0 in the cross section of the protective film B along the thickness direction.
  • the average aspect ratio of the rubber particles b is 1.2 or more, the rubber particles b tend to follow the deformation of the protective film B when the blade is pushed in in the punching step of the polarizing plate. Therefore, the stress received by the protective film B can be relaxed, and cracks and the like during punching of the polarizing plate can be suppressed.
  • the average aspect ratio of the rubber particles b is 3.0 or less, interfacial peeling between the rubber particles b and the (meth) acrylic resin can be less likely to occur.
  • the average aspect ratio of the rubber particles b is too high, the residual stress due to the stretching of the rubber particles b is also large, so that the plastic deformation of the (meth) acrylic resin and the plastic deformation of the rubber particles b are likely to deviate from each other. Meta) Voids are likely to be formed at the interface between the acrylic resin and the rubber particles b.
  • the average aspect ratio of the rubber particles b is 3.0 or less, the residual stress caused by such stretching can be reduced, so that interfacial peeling between the rubber particles b and the (meth) acrylic resin can be less likely to occur.
  • the average aspect ratio of the rubber particles b is more preferably 1.5 to 2.9.
  • the average major axis of the rubber particles b is preferably 250 to 400 nm.
  • the average major axis of the rubber particles a is 250 nm or more, not only sufficient toughness and flexibility can be imparted to the protective film B, but also the effect of relaxing stress can be easily obtained.
  • the average major axis of the rubber particles a is 400 nm or less, the effect of dispersing stress is not easily impaired.
  • the average major axis of the rubber particles b is the average value of the major axis of the rubber particles.
  • the average aspect ratio of the rubber particles b is defined in the same manner as the average aspect ratio of the rubber particles a, and can be measured by the same method.
  • the average major axis of the rubber particles b is defined in the same manner as the average major axis of the rubber particles a, and can be measured by the same method.
  • the average aspect ratio and average major axis of the rubber particles b can be adjusted according to the stretching conditions of the protective film B in the same manner as described above.
  • the monomer component and structure constituting the rubber particle b may be the same as the monomer component and structure constituting the rubber particle a.
  • the rubber particles b are core-shell type particles having a core portion containing an acrylic rubber-like polymer (b1) and a shell portion containing a polymer (b2) containing a structural unit derived from a methacrylic acid ester. sell.
  • the acrylic rubber-like polymer (b1) is the same as the acrylic rubber-like polymer (a1), and the composition may be the same or different.
  • the polymer (b2) is the same as the polymer (a2), and the composition may be the same or different.
  • the acrylic rubber-like polymer (b1) constituting the rubber particles b contains structural units derived from styrenes
  • the content of the structural units derived from styrenes of the rubber particles b contained in the protective film B is , It is preferable that the content of the rubber particles a contained in the protective film A is larger than the content of the structural unit derived from styrenes. That is, the content of the structural unit derived from the styrenes of the acrylic rubber-like polymer (b1) is preferably higher than the content of the structural unit derived from the styrenes of the acrylic rubber-like polymer (a1). ..
  • the content of the structural units derived from the styrenes of the rubber particles b is preferably 5 to 60% by mass with respect to all the structural units constituting the acrylic rubber-like polymer (b1). More preferably, it is 40 to 60% by mass.
  • the rubber particles b can be appropriately hardened, so that the tensile elastic modulus can be easily adjusted within the above range.
  • the glass transition temperature of the rubber particles b can be room temperature or lower (25 ° C. or lower) as described above. Further, the glass transition temperature of the rubber particles b is preferably higher than the glass transition temperature of the rubber particles a.
  • the content of the rubber particles b in the protective film B is not particularly limited, but is smaller than the content of the rubber particles a in the protective film A from the viewpoint of making the tensile elastic modulus of the protective film B higher than that of the protective film A. Is preferable.
  • the content of the rubber particles b in the protective film B is preferably 2 to 15% by mass, and more preferably 5 to 12% by mass with respect to the protective film B.
  • the protective film B may further contain components other than the above, if necessary.
  • the same component as the other component in the protective film A can be used.
  • the tensile elastic modulus of the protective film B is not particularly limited, but is preferably higher than the tensile elastic modulus of the protective film A from the viewpoint of facilitating suppression of cracks and delamination when punching the polarizing plate. This is because the stress generated in the protective film B by pushing the blade in the punching step of the polarizing plate is larger than the stress generated in the protective film A, and it is highly necessary to adjust the load applied to the rubber particles b in the protective film B.
  • the force received from the blade is easily dispersed in the resin; whereas if the circumference of the rubber particles b is a hard resin, the force received from the blade is distributed to the resin.
  • the rubber particles b are more susceptible to force without being diverged too much. That is, by appropriately increasing the tensile elastic modulus of the protective film B, it is possible to easily apply an appropriate load to the rubber particles b, so that the stress applied when punching the polarizing plate is easily absorbed by the rubber particles b, and the resin It can make it easier to prevent cracks from forming. As a result, it is possible to easily suppress cracks and delamination when punching the polarizing plate.
  • the difference in tensile elastic modulus between the protective film B and the protective film A at 25 ° C. can be, for example, 0.3 GPa or more.
  • the tensile elastic modulus of the protective film B at 25 ° C. is preferably 2.4 to 3.4 GPa.
  • the tensile elastic modulus of the protective film B can be measured by the same method as described above.
  • the tensile elastic modulus of the protective film B can be adjusted by the composition of the (meth) acrylic resin, the content and composition of the rubber particles b, and the like. From the viewpoint of increasing the tensile elastic modulus of the protective film B, it is derived from the structural unit (U2) derived from phenylmaleimide / (structural unit (U2) derived from phenylmaleimide) and the acrylic acid alkyl ester in the (meth) acrylic resin. It is preferable to increase the ratio of the structural units (U3) to be formed), decrease the content of the rubber particles b, or increase the content of the structural units derived from styrenes of the rubber particles b.
  • the haze of the protective film B is preferably 2.0% or less, and more preferably 1.0% or less, as described above.
  • the in-plane retardation Ro measured in an environment with a measurement wavelength of 550 nm and 23 ° C. and 55% RH is 0 to 10 nm. It is preferably 0 to 5 nm, and more preferably 0 to 5 nm.
  • the phase difference Rt in the thickness direction of the protective film B is preferably ⁇ 20 to 20 nm, and more preferably ⁇ 10 to 10 nm.
  • the in-plane slow-phase axis of the protective film B can be confirmed by an automatic birefringence meter Axoscan (AxoScan Mueller Matrix Polarimeter: manufactured by Axometrics).
  • Ro and Rt can be measured by the following methods. 1) The protective film is humidity-controlled for 24 hours in an environment of 23 ° C. and 55% RH. The average refractive index of this film is measured with an Abbe refractometer, and the thickness d is measured with a commercially available micrometer. 2) The retardation Ro and Rt of the film after humidity control at a measurement wavelength of 550 nm were measured at 23 ° C. and 55% RH using an automatic birefringence meter Axoscan (Axo Scan Mueller Matrix Matrix Polarimeter), respectively. Measure in the environment.
  • the phase difference Ro and Rt of the protective film B can be adjusted by, for example, the monomer composition of the (meth) acrylic resin and the stretching conditions.
  • a (meth) acrylic resin that does not easily generate a phase difference due to stretching is used (for example, a structural unit derived from a monomer having negative birefringence and a positive birefringence. It is preferable to set the monomer ratio so that the phase difference can be offset with the structural unit derived from the monomer having.
  • the protective film B Since the protective film B is preferably formed by a casting method, it may further contain a residual solvent.
  • the amount of residual solvent is preferably 700 ppm or less, more preferably 30 to 700 ppm, based on the protective film B.
  • the content of the residual solvent can be adjusted by the drying conditions of the dope cast on the support in the process of manufacturing the protective film.
  • the amount of residual solvent in the protective film B can be measured by headspace gas chromatography.
  • a sample is sealed in a container, heated, and the gas in the container is promptly injected into a gas chromatograph with the container filled with volatile components, and mass spectrometry is performed to identify the compound.
  • the volatile components are quantified while doing so.
  • the thickness of the protective film B is not particularly limited, but is preferably thinner than the thickness of the protective film A.
  • the thickness of the protective film B is relatively thin, not only can the blade be less likely to be caught when the blade is punched in the punching step of the polarizing plate, but also physical deformation when the blade is pushed in can be reduced. As a result, cracks when punching the polarizing plate can be further suppressed.
  • the thickness of the protective film B can be 20 to 77% of the thickness of the protective film A.
  • the thickness of the protective film B is preferably 10 to 60 ⁇ m, more preferably 10 to 40 ⁇ m.
  • Protective films A and B may be manufactured by any method, may be manufactured by a solution casting method (cast method), or may be manufactured by a melt casting method (melt). You may.
  • the protective film A can be manufactured by, for example, a melt casting method (melt).
  • a melt casting method melt
  • a step of melt-extruding a resin composition containing a (meth) acrylic resin and rubber particles a step of cooling and solidifying the extruded resin composition, and cooling as necessary.
  • a protective film can be obtained through a step of stretching a film-like substance obtained by solidification.
  • the draw ratio when the protective film A is manufactured is not particularly limited, but is lower than the draw ratio when the protective film B is manufactured, for example, from the viewpoint of making the average aspect ratio of the rubber particles a smaller than that of the rubber particles b. It is preferably 10% or less, and more preferably unstretched.
  • the protective film B is preferably manufactured by the casting method from the viewpoint of reducing the restrictions on the materials that can be used. That is, the protective film A has at least 1) a step of obtaining a dope containing the above-mentioned (meth) acrylic resin, rubber particles, and a solvent, and 2) after casting the obtained dope onto a support. It can be produced through a step of obtaining a film-like substance by drying and peeling, and a step of 3) drying the obtained film-like substance while stretching it if necessary.
  • a (meth) acrylic resin and rubber particles a or b (hereinafter collectively referred to as “rubber particles”) are dissolved or dispersed in a solvent to prepare a dope.
  • the solvent used for doping includes at least an organic solvent (good solvent) capable of dissolving the (meth) acrylic resin.
  • good solvents include chlorine-based organic solvents such as methylene chloride; non-chlorine-based organic solvents such as methyl acetate, ethyl acetate, acetone and tetrahydrofuran. Of these, methylene chloride is preferable.
  • the solvent used for doping may further contain a poor solvent.
  • poor solvents include straight-chain or branched-chain aliphatic alcohols having 1 to 4 carbon atoms. When the ratio of alcohol in the doping is high, the film-like substance tends to gel and peels off from the metal support easily.
  • linear or branched aliphatic alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, and tert-butanol. Of these, ethanol is preferable because of its stability of doping, relatively low boiling point, and good drying property.
  • the dope obtained in step 2) is cast on the support. Doping can be cast by discharging from a casting die.
  • the solvent in the dope cast on the support is evaporated and dried.
  • the dried dope is stripped from the support to give a film.
  • the residual solvent amount of the doping when peeling from the support is preferably, for example, 25% by mass or more, and more preferably 30 to 37% by mass.
  • the amount of residual solvent at the time of peeling is 37% by mass or less, it is easy to prevent the film-like material from being excessively stretched due to peeling.
  • the heat treatment for measuring the amount of residual solvent means a heat treatment at 140 ° C. for 30 minutes.
  • the amount of residual solvent at the time of peeling can be adjusted by adjusting the drying temperature and drying time of the doping on the support, the temperature of the support, and the like.
  • the obtained film-like material is dried. Drying may be performed in one step or in multiple steps. Further, drying may be carried out while stretching, if necessary.
  • the drying step of the film-like material includes a step of pre-drying the film-like material (pre-drying step), a step of stretching the film-like material (stretching step), and a step of drying the stretched film-like material (main Drying step) and may be included.
  • the pre-drying temperature (drying temperature before stretching) can be higher than the stretching temperature.
  • the glass transition temperature of the (meth) acrylic resin is Tg, it is preferably Tg (° C.) or higher, and more preferably (Tg + 10) to (Tg + 50) ° C.
  • the pre-drying temperature is Tg (° C.) or higher, preferably (Tg + 10) ° C. or higher, the solvent is likely to be volatilized appropriately, so that the transportability (handleability) is easily improved. Is not excessively volatilized, so that the stretchability in the subsequent stretching step is not easily impaired.
  • the initial drying temperature can be measured as (a) an atmospheric temperature such as the temperature inside the stretching machine or the hot air temperature when the drying is performed by the non-contact heating type while being conveyed by a tenter stretching machine or a roller.
  • Stretching may be performed according to the required optical characteristics, and is preferably stretched in at least one direction, and stretches in two directions orthogonal to each other (for example, the width direction (TD direction) of the film-like object and orthogonal to it. Biaxial stretching in the transport direction (MD direction)) may be performed.
  • the draw ratio when the protective film B is manufactured may be higher than the stretch ratio when the protective film A is manufactured.
  • the draw ratio when producing the protective film B is preferably 40 to 100%, more preferably 60 to 100%.
  • the stretching ratio in each direction is within the above range.
  • the stretch ratio (%) is defined as (size of the film after stretching in the stretching direction-size of the film before stretching in the stretching direction) / (size of the film before stretching in the stretching direction) ⁇ 100.
  • the stretching temperature (drying temperature during stretching) is preferably Tg (° C.) or higher, and is preferably (Tg + 10) to (Tg + 50), when the glass transition temperature of the (meth) acrylic resin is Tg, as described above. More preferably, it is ° C.
  • Tg glass transition temperature
  • the stretching temperature during production of the protective film B can be, for example, 115 ° C. or higher.
  • the stretching temperature it is preferable to measure the ambient temperature such as (a) the temperature inside the stretching machine, as described above.
  • the amount of residual solvent in the film-like material at the start of stretching is preferably about the same as the amount of residual solvent in the film-like material at the time of peeling, for example, preferably 20 to 30% by mass, and 25 to 30% by mass. More preferably.
  • Stretching of the film-like object in the TD direction can be performed by, for example, fixing both ends of the film-like object with clips or pins and widening the distance between the clips or pins in the traveling direction (tenter method).
  • Stretching of the film-like material in the MD direction can be performed by, for example, a method (roll method) in which a plurality of rolls are provided with a peripheral speed difference and the roll peripheral speed difference is used between them.
  • the main drying temperature (drying temperature in the case of unstretched) is preferably (Tg-50) to (Tg-30) ° C., where Tg is the glass transition temperature of the (meth) acrylic resin, and (Tg). More preferably, it is ⁇ 40) to (Tg-30) ° C.
  • Tg glass transition temperature of the (meth) acrylic resin
  • Tg the glass transition temperature of the (meth) acrylic resin
  • Tg the post-drying temperature
  • the main drying temperature it is preferable to measure the ambient temperature such as (a) hot air temperature as described above.
  • Adhesive layers A and B The adhesive layer A is arranged between the protective film A and the polarizer and adheres them. Similarly, the adhesive layer B is placed between the protective film B and the polarizer and adheres them.
  • the adhesive layers A and B may be layers obtained from a completely saponified polyvinyl alcohol aqueous solution (water glue), or may be a cured product layer of an active energy ray-curable adhesive. From the viewpoint of having high affinity with the protective films A and B containing the (meth) acrylic resin and facilitating good adhesion, the adhesive layers A and B are cured product layers of the active energy ray-curable adhesive. Is preferable.
  • the active energy ray-curable adhesive may be a photoradical polymerizable composition or a photocationic polymerizable composition. Of these, a photocationically polymerizable composition is preferable.
  • the photocationic polymerizable composition contains an epoxy compound and a photocationic polymerization initiator.
  • the epoxy compound is a compound having one or more, preferably two or more epoxy groups in the molecule.
  • epoxy compounds include hydrogenated epoxy compounds obtained by reacting an alicyclic polyol with epichlorohydrin (glycidyl ether of a polyol having an alicyclic ring); an aliphatic polyhydric alcohol or an alkylene thereof.
  • Aliphatic epoxy compounds such as polyglycidyl ether as an oxide adduct; include alicyclic epoxy compounds having one or more alicyclic ring-bonded epoxy groups in the molecule. Only one type of epoxy compound may be used, or two or more types may be used in combination.
  • the photocationic polymerization initiator may be, for example, an aromatic diazonium salt; an onium salt such as an aromatic iodonium salt or an aromatic sulfonium salt; an iron-alene complex or the like.
  • the photocationic polymerization initiator may be a cationic polymerization accelerator such as oxetane or polyol, a photosensitizer, an ion trapping agent, an antioxidant, a chain transfer agent, a tackifier, a thermoplastic resin, a filler, or a fluidized agent, if necessary.
  • Additives such as modifiers, plasticizers, defoamers, antistatic agents, leveling agents, solvents and the like may be further included.
  • the thicknesses of the adhesive layers A and B are not particularly limited, but may be, for example, 0.01 to 10 ⁇ m, preferably about 0.01 to 5 ⁇ m.
  • Adhesive layer The adhesive layer is arranged on the surface of the protective film B of the polarizing plate on the side opposite to the polarizer.
  • the polarizing plate of the present invention is bonded to a display element such as a liquid crystal cell via the pressure-sensitive adhesive layer.
  • the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is not particularly limited, and may be, for example, an acrylic pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, or the like. Acrylic adhesives are preferable from the viewpoints of transparency, weather resistance, heat resistance, and processability.
  • Adhesives include tackifiers, plasticizers, glass fibers, glass beads, metal powders, other fillers, pigments, colorants, fillers, antioxidants, UV absorbers, silane coupling agents, etc., as required. , Various additives may be further included.
  • the thickness of the pressure-sensitive adhesive layer is usually about 3 to 100 ⁇ m, preferably 5 to 50 ⁇ m.
  • the surface of the adhesive layer is protected by a release film that has undergone a mold release treatment.
  • the release film include plastic films such as acrylic films, polycarbonate films, polyester films and fluororesin films.
  • the polarizing plate of the present invention has a step of 1) laminating and bonding a protective film A on one surface of a polarizing element via an adhesive, and 2) bonding to the other surface of the polarizing element.
  • a step of laminating and laminating the protective film B via an agent and 3) a step of laminating the adhesive layer and the protective film on the bonded laminated protective film B to obtain a polarizing plate. can get.
  • an active energy ray-curable adhesive is used as the adhesive will be described.
  • step 1) The surface of the protective film A is subjected to surface treatment such as corona treatment as necessary.
  • a protective film A is applied to one surface of the polarizing element via a layer of an active energy ray-curable adhesive (in the case of surface treatment, the surface-treated surface of the protective film A is on the polarizer side).
  • the active energy ray-curable adhesive is cured by irradiating it with active energy rays.
  • the polarizer and the protective film A are bonded to each other via the cured product layer of the active energy ray-curable adhesive.
  • the surface of the protective film B is subjected to a surface treatment such as a corona treatment, if necessary.
  • a protective film B is applied to the other surface of the polarizer via a layer of an active energy ray-curable adhesive (in the case of surface treatment, the surface-treated surface of the protective film B is on the polarizer side).
  • the active energy ray-curable adhesive is cured by irradiating it with active energy rays.
  • the polarizer and the protective film B are bonded to each other via the cured product layer of the active energy ray-curable adhesive.
  • the steps 1) and 2) may be performed simultaneously or sequentially. From the viewpoint of increasing production efficiency, it is preferable that the steps 1) and 2) are performed at the same time.
  • the protective film A, the polarizer, and the protective film B are laminated by a roll-to-roll method. Then, the obtained laminate may be irradiated with active energy rays to cure the active energy ray-curable adhesive.
  • the pressure-sensitive adhesive layer and its release film are attached onto the protective film B of the obtained polarizing plate.
  • the pressure-sensitive adhesive layer can be formed by a method such as transferring a release film provided with the pressure-sensitive adhesive layer on the protective film B.
  • the obtained polarizing plate can be a long polarizing plate.
  • the elongated polarizing plate is wound into a roll to form a rolled body of the polarizing plate.
  • the roll body of the polarizing plate is unwound at the time of use (for example, at the time of manufacturing the display device), and then punched into an arbitrary size and shape to be used for manufacturing the display device.
  • the punching of the polarizing plate is performed by pushing the blade from the protective film A side (see FIG. 2A).
  • the display device of the present invention includes the polarizing plate of the present invention.
  • the display device of the present invention is a liquid crystal display device, an organic EL display device, or the like, and may be a liquid crystal display device.
  • the liquid crystal display device of the present invention includes a liquid crystal cell, a first polarizing plate arranged on one surface of the liquid crystal cell, and a second polarizing plate arranged on the other surface of the liquid crystal cell.
  • the display modes of the liquid crystal cells are, for example, STN (Super-Twisted Nematic), TN (Twisted Nematic), OCB (Optically Compensated Bend), HAN (Hybridaligned Nematic), VA (Vertical Alignment, MVA (Multi-domain Vertical Alignment), PVA). (Patterned Vertical Alignment)), IPS (In-Plane-Switching), etc.
  • STN Super-Twisted Nematic
  • TN Transmission Nematic
  • OCB Optically Compensated Bend
  • HAN Hybridaligned Nematic
  • VA Very Alignment
  • MVA Multi-domain Vertical Alignment
  • PVA Parallel-Plane-Switching
  • the IPS mode is preferable.
  • first polarizing plate and the second polarizing plate can be the polarizing plate of the present invention.
  • the polarizing plate of the present invention is arranged so that the pressure-sensitive adhesive layer is in close contact with the liquid crystal cell.
  • the glass transition temperature and weight average molecular weight of the (meth) acrylic resins 1 to 9 were measured by the following methods.
  • the glass transition temperature (Tg) of the (meth) acrylic resin was measured using DSC (Differential Scanning Colorimetry) according to JIS K 7121-2012.
  • the weight average molecular weight (Mw) of the (meth) acrylic resin was measured using gel permeation chromatography (HLC8220GPC manufactured by Tosoh Corporation) and a column (TSK-GEL G6000HXL-G5000HXL-G5000HXL-G4000HXL-G3000HXL series manufactured by Tosoh Corporation). .. 20 mg ⁇ 0.5 mg of the sample was dissolved in 10 ml of tetrahydrofuran and filtered through a 0.45 mm filter. 100 ml of this solution was injected into a column (temperature 40 ° C.), measured at a detector RI temperature of 40 ° C., and a styrene-converted value was used.
  • the internal temperature was adjusted to 80 ° C., 27 parts by mass of the monomer mixture (1-1) (70.9% by mass of methyl methacrylate, 12.5% by mass of butyl acrylate, 16 styrene).
  • the obtained latex was salted out with magnesium chloride, solidified, washed with water, and dried to obtain a white powdery graft copolymer (rubber particles R1).
  • the graft ratio of the rubber particles R1 was 24.2%, the amount of styrene was 40% by mass, the glass transition temperature (Tg) was 5 ° C., and the average particle size was 200 nm.
  • the average particle size of the rubber particles R1 to R5 was measured by the following method.
  • the dispersed particle size of the rubber particles in the obtained dispersion was measured by a zeta potential / particle size measuring system (ELSZ-2000ZS manufactured by Otsuka Electronics Co., Ltd.).
  • the content of the structural unit derived from styrenes of the rubber particles was measured by the method calculated from the area ratio of the peak detected by the above-mentioned thermal decomposition GC / MS.
  • the measurement conditions for GCMS were as follows.
  • Measuring device SHIMAZU GCMS QP2010 Column type: Ultra Alloy-5 (size 30 m x diameter 0.25 mm) Carrier gas type: He Flow rate condition: 1.8 mL / min Column oven temperature condition: 40 ° C-10 ° C / min-320 ° C Interface temperature: 300 ° C Ion source temperature: 200 ° C Detection mode: SIM (target ion: m / z104, confirmed ion: m / z78)
  • protective film 2-1 Preparation of protective film A ⁇ Production of protective film 101>
  • the pellet of the (meth) acrylic resin 1 and the rubber particles R1 were dried at 80 ° C. for 4 hours in a dryer and then supplied to a ⁇ 65 mm single-screw extruder.
  • the molten resin was extruded from the T-die by heating and melting at the extruder outlet so that the resin temperature became 270 ° C.
  • the resin temperature immediately after 3 discharges at the T-die outlet was 270 ° C.
  • the discharged molten resin was sandwiched between a cast roll adjusted to 70 ° C. and a touch roll adjusted to 70 ° C., and cooled and solidified. Then, after continuously slitting both ends of the obtained film, the film was wound while being taken up by a take-up roll to obtain a protective film 101 having a thickness of 55 ⁇ m.
  • a protective film 102 was obtained in the same manner as the protective film 101 except that the film obtained after cooling and solidification was stretched under the conditions shown in Table 3.
  • a protective film 103 was obtained in the same manner as the protective film 101 except that the rubber particles R1 were not added and the film was stretched under the conditions shown in Table 3.
  • ⁇ Preparation of protective film 104> (Preparation of rubber particle dispersion) 11.3 parts by mass of rubber particles R2 and 200 parts by mass of methylene chloride were stirred and mixed with a dissolver for 50 minutes, and then dispersed under a condition of 1500 rpm using a milder disperser (manufactured by Pacific Machinery & Engineering Co., Ltd.). A rubber particle dispersion was obtained.
  • a dope having the following composition was prepared. First, methylene chloride and ethanol were added to the pressurized dissolution tank. Next, the (meth) acrylic resin 2 was charged into the pressure dissolution tank with stirring. Then, the rubber particle dispersion liquid prepared above was added, and this was completely dissolved while stirring. This was filtered using SHP150 manufactured by Roki Techno Co., Ltd. to obtain a doping.
  • the dope was uniformly cast on the stainless belt support at a temperature of 30 ° C. and a width of 1800 mm using an endless belt casting device.
  • the temperature of the stainless steel belt was controlled to 28 ° C.
  • the transport speed of the stainless steel belt was 20 m / min.
  • the solvent was evaporated on the stainless belt support until the amount of residual solvent in the cast dope reached 30% by mass. Then, it was peeled from the stainless belt support at a peeling tension of 128 N / m to obtain a film-like material. That is, the amount of residual solvent in the film-like substance at the time of peeling was 30% by mass.
  • the peeled film was further dried while being conveyed by a large number of rollers to obtain a protective film 104 having a film thickness of 55 ⁇ m.
  • the average aspect ratio and average major axis of the rubber particles were calculated by the following procedure. 1) Of the cross sections along the thickness direction of the protective film, the cross section parallel to the TD direction of the protective film was observed by TEM. The observation area was 5 ⁇ m ⁇ 5 ⁇ m. 2) In the obtained TEM image, the major axis and the minor axis of each rubber particle were measured, and the aspect ratio was calculated. 3) The above operations 1) and 2) were performed at a total of 4 locations with different observation areas. Then, the average value of the measured aspect ratios was defined as the "average aspect ratio", and the average value of the measured major axes was defined as the "average major axis".
  • the obtained protective film was cut into 1 cm (TD direction) ⁇ 10 cm (MD direction) to prepare a sample piece, and the humidity was adjusted for 24 hours in an environment of 25 ° C. and 60% RH.
  • the tensile elastic modulus of the obtained sample piece was measured by the tensile test method described in JIS K7127. Specifically, the sample piece was set in a Tensilon manufactured by Orientec Co., Ltd., and the tensile elastic modulus was measured when the tensile test was performed under the conditions of a distance between chucks of 50.0 mm and a tensile speed of 50 mm / min. The measurement was performed at 25 ° C. and 60% RH.
  • Table 3 shows the evaluation results of the protective films 101 to 108.
  • the content of the rubber particles in Table 3 indicates the amount with respect to the protective film. The same applies to Tables 4 and 5.
  • a dope having the following composition was prepared. First, methylene chloride and ethanol were added to the pressurized dissolution tank. Next, the (meth) acrylic resin was charged into the pressure dissolution tank with stirring. Then, the rubber particle dispersion liquid prepared above was added, and this was completely dissolved while stirring. This was filtered using SHP150 manufactured by Roki Techno Co., Ltd. to obtain a doping.
  • the dope was uniformly cast on the stainless belt support at a temperature of 30 ° C. and a width of 1800 mm using an endless belt casting device.
  • the temperature of the stainless steel belt was controlled to 28 ° C.
  • the transport speed of the stainless steel belt was 20 m / min.
  • the solvent was evaporated on the stainless belt support until the amount of residual solvent in the cast dope reached 30% by mass. Then, it was peeled from the stainless belt support at a peeling tension of 128 N / m to obtain a film-like material. The amount of residual solvent in the film-like material at the time of peeling was 30% by mass.
  • the obtained film-like material was stretched by 70% in the width direction (TD direction) under the condition of 60 ° C. (Tg-60 ° C.) with a tenter. Then, the film was further dried at 140 ° C. (Tg + 40 ° C.) while being conveyed by a roll, and the end portion sandwiched between the tenter clips was slit with a laser cutter and wound up to obtain a protective film 201 having a film thickness of 20 ⁇ m.
  • Protective films 202 to 205 were obtained in the same manner as the protective film 201 except that the stretching conditions were changed as shown in Table 4.
  • a protective film 206 was obtained in the same manner as the protective film 201 except that the rubber particles R3 were not added and the stretching conditions were changed as shown in Table 4.
  • Protective films 207 to 212 were obtained in the same manner as the protective film 201 except that the type of the (meth) acrylic resin was changed as shown in Table 4. Regarding the protective film 207, the stretching conditions were also changed as shown in Table 4.
  • the protective film 101 is arranged on one surface of the produced polarizing element via the ultraviolet curable adhesive layer, and the protective film 201 is arranged on the other surface via the ultraviolet curable adhesive layer.
  • the obtained laminate was irradiated with ultraviolet rays so that the integrated light amount was 750 mJ / cm 2 using an ultraviolet irradiation device with a belt conveyor (the lamp uses a D bulb manufactured by Fusion UV Systems).
  • the UV curable adhesive layer was cured.
  • the adhesive layer (thickness 20 ⁇ m) of the following PET film with an adhesive layer was bonded onto the obtained laminated protective film B.
  • a polarizing plate 301 having a laminated structure of protective film 101 (protective film A) / adhesive layer / polarizer / adhesive layer / protective film 201 (protective film B) / adhesive layer / PET film was obtained.
  • the pressure-sensitive adhesive layer is obtained by applying an acrylic pressure-sensitive adhesive composition containing a (meth) acrylic polymer and a cross-linking agent onto a PET film and then heat-drying (partially cross-linking) the pressure-sensitive adhesive layer.
  • Polarizing plates 302 to 323 were obtained in the same manner as the polarizing plate 301 except that the protective films A and B were changed as shown in Table 5.
  • FIG. 3A and 3B are diagrams showing a punching process of the polarizing plate 100 in the examples.
  • FIG. 3A is a perspective view of the polarizing plate 100
  • FIG. 3B is a partial cross-sectional view taken along the line AA.
  • the obtained polarizing plate 100 was bonded onto the PET film 170 via the pressure-sensitive adhesive layer 140. Then, as shown in FIG. 3A, nine 1 m square polarizing plates 100 (W in FIG. 3A is 1 m) were punched out into a 10 cm square square plate 100 bonded to the PET film 170. The gap p between adjacent polarizing plates was set to 1 cm.
  • ⁇ Unable to recognize unevenness on the display panel
  • ⁇ Very slight unevenness on the display panel does not affect the quality
  • ⁇ Local unevenness is seen on the display panel, but the boundary between the uneven part and the non-uneven part Is not visible
  • ⁇ Local unevenness is seen on the display panel, and the boundary between the uneven part and the non-uneven part can be seen.
  • ⁇ The uneven part is seen on the entire surface of the display panel, and the uneven part and the non-uneven part are clearly visible. it can ⁇ ⁇ , ⁇ and ⁇ are practically acceptable levels.
  • Table 5 shows the configurations and evaluation results of the obtained polarizing plates 301 to 323.
  • the punching property is further enhanced and display unevenness can be further suppressed (comparison between the polarizing plate 320 and 322 or 317). ). It is considered that this is because the protective film B has an appropriate hardness, so that the deformation due to the pushing of the blade is small and the stress generated by the deformation can be reduced.
  • the punching property is further enhanced and the display unevenness can be further suppressed (comparison between the polarizing plates 301 and 323).
  • the protective film B is moderately thin, which makes it difficult for the blade to get caught when the blade is pulled out, which makes it easier to suppress cracks; and the thin protective film B makes it physically when the blade is pushed in. It is considered that this is because the deformation (strain) is reduced and the stress generated is reduced.
  • the polarizing plates 305 to 309 and 313 to 314 all have poor punching properties and display unevenness. Further, it can be seen that the polarizing plate 304 (comparative example) causes display unevenness. Specifically, it is considered that the polarizing plate 305 could not sufficiently relieve the stress because the average aspect ratio of the rubber particles b in the protective film B was low.
  • the reason why the display unevenness of the polarizing plate 304 is poor is that the average aspect ratio of the rubber particles b in the protective film B is high, so that the residual stress is also high, and the plastic deformation of the rubber particles b and the plastic deformation of the (meth) acrylic resin It is probable that the rubber particles b and the (meth) acrylic resin are easily separated from each other, and as a result, the delamination between the protective film B and the adhesive layer is caused. Since the protective film B does not contain the rubber particles b, the polarizing plate 307 is considered to be too brittle to withstand deformation during punching, resulting in cracks and chips.
  • the protective film A does not contain the rubber particles a, it is considered that the protective film A is likely to be cracked at the time of punching.
  • the punching property and display unevenness are low because the average aspect ratio of the rubber particles a in the protective film A is too high, so that the rubber particles a easily follow the deformation of the protective film A, and the protective film B It is probable that the stress applied to the film increased.
  • the punching property and display unevenness are low because the ratio of PMI of the protective film B is too large, the brittleness of the film becomes high, the rubber particles b are easily overloaded, and the resin It is probable that the load was easily applied.
  • the polarizing plate 309 has lower display unevenness than the polarizing plate 306. This is because the (meth) acrylic resin contained in the protective film B used for the polarizing plate 309 does not contain a structural unit derived from phenylmaleimide, so that the interface between the rubber particles b and the (meth) acrylic resin It is probable that the peeling occurred.
  • a polarizing plate capable of suppressing cracks and delamination during punching and reducing display unevenness due to keystrokes when used for a long time in a high humidity environment.
  • Polarizing plate 110 Polarizer 120A Protective film (Protective film A) 120B protective film (protective film B) 130A, 130B Adhesive layer 140 Adhesive layer 150a Rubber particles (rubber particles a) 150b rubber particles (rubber particles b)

Abstract

A polarizing plate according to the present invention sequentially comprises a protective film A, a polarizer, a protective film B and an adhesive layer in this order. The protective film A contains a (meth)acrylic resin and rubber particles a. The protective film B contains a (meth)acrylic resin and rubber particles b. In a cross-section of the protective film A, the average aspect ratio of the rubber particles is from 1.0 to 1.1; and in a cross-section of the protective film B, the average aspect ratio of the rubber particles is from 1.2 to 3.0. The (meth)acrylic resin contained in the protective film B is a copolymer that contains 50-95% by mass of a structural unit derived from methyl methacrylate, 1-25% by mass of a structural unit derived from a phenyl maleimide and 1-25% by mass of a structural unit derived from an acrylic acid alkyl ester.

Description

偏光板Polarizer
　本発明は、偏光板に関する。 The present invention relates to a polarizing plate.
　液晶表示装置などの表示装置に用いられる偏光板は、偏光子と、その両面に配置された保護フィルムとを含む。保護フィルムとしては、優れた透明性や寸法安定性、低吸湿性を有することから、ポリメチルメタクリレートなどの（メタ）アクリル系樹脂を主成分として含むフィルムが用いられている。 A polarizing plate used in a display device such as a liquid crystal display device includes a polarizing element and protective films arranged on both sides thereof. As the protective film, a film containing a (meth) acrylic resin such as polymethylmethacrylate as a main component is used because it has excellent transparency, dimensional stability, and low hygroscopicity.
　一方で、（メタ）アクリル系樹脂フィルムは脆いことから、脆さを解消するために、ゴム粒子などの弾性体粒子がさらに添加されて使用されている。 On the other hand, since the (meth) acrylic resin film is brittle, elastic particles such as rubber particles are further added and used in order to eliminate the brittleness.
　そのような（メタ）アクリル系樹脂フィルムを用いた偏光板としては、偏光子と、その両面に配置された２つの保護フィルムとを含み、２つの保護フィルムが、弾性体粒子を含むポリメチルメタクリレートのコア層と、その両面に配置された弾性体粒子を含まない２つのポリメチルメタクリレートの２つのスキン層とを有する共押出フィルムである偏光板が知られている（例えば特許文献１）。２つの保護フィルムとしては、同一のフィルムが用いられている。 A polarizing plate using such a (meth) acrylic resin film includes a polarizing element and two protective films arranged on both sides thereof, and the two protective films are polymethylmethacrylate containing elastic particles. There is known a polarizing plate which is a co-extruded film having a core layer of the above and two skin layers of two polymethylmethacrylates which do not contain elastic particles arranged on both sides thereof (for example, Patent Document 1). The same film is used as the two protective films.
　このような偏光板は、製品である表示装置を製造する際、製品に合わせて所定の大きさおよび形状に打ち抜かれる。 Such a polarizing plate is punched into a predetermined size and shape according to the product when manufacturing a display device which is a product.
特開２００８－４０２７５号公報Japanese Unexamined Patent Publication No. 2008-40275
　近年、生産収率の向上の観点などから、偏光板を刃で打ち抜く際に、偏光板同士の余白分をこれまで以上に狭くすることが求められている。特許文献１の偏光板に用いられた保護フィルムは弾性体粒子を含むにも係わらず、偏光板の打ち抜き時のひび割れ（クラック）を抑制しきれず、偏光板同士の余白分を狭くすることができなかった。 In recent years, from the viewpoint of improving the production yield, when punching a polarizing plate with a blade, it is required to narrow the margin between the polarizing plates more than ever. Although the protective film used for the polarizing plate of Patent Document 1 contains elastic particles, it cannot completely suppress cracks during punching of the polarizing plates, and the margins between the polarizing plates can be narrowed. There wasn't.
　また、偏光板の打ち抜き工程において、偏光板から刃を引き抜く際に、（メタ）アクリル系樹脂フィルムと偏光子との間で剥離が生じやすく、層間密着性が低下しやすい。このように、層間密着性が低下した偏光板を有する表示装置は、高湿環境下で長時間使用した際に、打鍵による表示ムラを生じやすい。 Further, in the punching process of the polarizing plate, when the blade is pulled out from the polarizing plate, peeling easily occurs between the (meth) acrylic resin film and the polarizing element, and the interlayer adhesion tends to decrease. As described above, a display device having a polarizing plate having reduced interlayer adhesion is likely to cause display unevenness due to keystrokes when used for a long time in a high humidity environment.
　本発明は、上記事情に鑑みてなされたものであり、打ち抜き時のクラックや層間剥離を抑制でき、高湿環境下での長時間使用した際の打鍵による表示ムラを低減できる偏光板を提供することを目的とする。 The present invention has been made in view of the above circumstances, and provides a polarizing plate capable of suppressing cracks and delamination during punching and reducing display unevenness due to keystrokes when used for a long time in a high humidity environment. The purpose is.
　上記課題は、以下の構成によって解決することができる。 The above problem can be solved by the following configuration.
　本発明の偏光板は、偏光子と、前記偏光子の一方の面に配置された保護フィルムＡと、前記偏光子の他方の面に配置された保護フィルムＢと、前記保護フィルムＢの前記偏光子とは反対側の面に配置された粘着剤層とを含む偏光板であって、前記保護フィルムＡは、（メタ）アクリル系樹脂と、ゴム粒子ａとを含み、前記保護フィルムＢは、（メタ）アクリル系樹脂と、ゴム粒子ｂとを含み、前記保護フィルムＡの厚み方向に沿った断面において、前記ゴム粒子ａの平均アスペクト比は、１．０～１．１であり、前記保護フィルムＢの厚み方向に沿った断面において、前記ゴム粒子ｂの平均アスペクト比は、１．２～３．０であり、前記保護フィルムＢに含まれる前記（メタ）アクリル系樹脂は、前記（メタ）アクリル系樹脂を構成する全構造単位に対して、５０～９５質量％のメタクリル酸メチルに由来する構造単位と、１～２５質量％のフェニルマレイミドに由来する構造単位と、１～２５質量％のアクリル酸アルキルエステルに由来する構造単位とを含む共重合体である。 The polarizing plate of the present invention comprises a polarizer, a protective film A arranged on one surface of the polarizer, a protective film B arranged on the other surface of the polarizer, and the polarization of the protective film B. A polarizing plate including an adhesive layer arranged on a surface opposite to the child, the protective film A contains a (meth) acrylic resin and rubber particles a, and the protective film B is a protective film B. The average aspect ratio of the rubber particles a is 1.0 to 1.1 in a cross section along the thickness direction of the protective film A, which contains the (meth) acrylic resin and the rubber particles b, and the protection. In the cross section along the thickness direction of the film B, the average aspect ratio of the rubber particles b is 1.2 to 3.0, and the (meth) acrylic resin contained in the protective film B is the (meth) acrylic resin. ) With respect to all the structural units constituting the acrylic resin, 50 to 95% by mass of the structural unit derived from methyl methacrylate, 1 to 25% by mass of the structural unit derived from phenylmaleimide, and 1 to 25% by mass of the structural unit. It is a copolymer containing a structural unit derived from the acrylic acid alkyl ester of.
　本発明によれば、打ち抜き時のクラックや層間剥離を抑制でき、高湿環境下での長時間使用した際の打鍵による表示ムラを低減できる偏光板を提供することができる。 According to the present invention, it is possible to provide a polarizing plate capable of suppressing cracks and delamination during punching and reducing display unevenness due to keystrokes when used for a long time in a high humidity environment.
図１は、本発明の一実施の形態に係る偏光板を示す断面図である。FIG. 1 is a cross-sectional view showing a polarizing plate according to an embodiment of the present invention. 図２は、偏光板の打ち抜き工程における推定機構を説明する断面図である。FIG. 2 is a cross-sectional view illustrating an estimation mechanism in the punching process of the polarizing plate. 図３ＡおよびＢは、実施例における偏光板の打ち抜き工程を示す図である。3A and 3B are diagrams showing a punching step of a polarizing plate in an example.
　以下、本発明の実施の形態について、図面を参照して詳細に説明する。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
　１．偏光板
　図１は、本実施の形態に係る偏光板１００を示す断面図である。 1. 1. Polarizing plate FIG. 1 is a cross-sectional view showing a polarizing plate 100 according to the present embodiment.
　図１に示されるように、本実施の形態に係る偏光板１００は、偏光子１１０（偏光子）と、その一方の面に配置され、かつゴム粒子１５０ａ（ゴム粒子ａ）を含む保護フィルム１２０Ａ（保護フィルムＡ）と、他方の面に配置され、かつゴム粒子１５０ｂ（ゴム粒子ｂ）を含む保護フィルム１２０Ｂ（保護フィルムＢ）と、保護フィルム１２０Ａと偏光子１１０との間に配置された接着剤層１３０Ａ（接着剤層Ａ）と、保護フィルム１２０Ｂと偏光子１１０との間に配置された接着剤層１３０Ｂ（接着剤層Ｂ）とを有する。 As shown in FIG. 1, the polarizing plate 100 according to the present embodiment is a protective film 120A arranged on a polarizing element 110 (polarizer) and one surface thereof and containing rubber particles 150a (rubber particles a). (Protective film A), a protective film 120B (protective film B) arranged on the other surface and containing rubber particles 150b (rubber particles b), and an adhesion arranged between the protective film 120A and the polarizer 110. It has an agent layer 130A (adhesive layer A) and an adhesive layer 130B (adhesive layer B) arranged between the protective film 120B and the polarizer 110.
　また、偏光板１００は、保護フィルム１２０Ｂの偏光子１１０とは反対側の面に配置された粘着剤層１４０をさらに有する。粘着剤層１４０は、偏光板１００を、液晶セルなどの表示素子（不図示）に貼り付けるための層である。粘着剤層１４０の表面は、通常、剥離フィルム（不図示）で保護されている。 Further, the polarizing plate 100 further has an adhesive layer 140 arranged on the surface of the protective film 120B opposite to the polarizer 110. The pressure-sensitive adhesive layer 140 is a layer for attaching the polarizing plate 100 to a display element (not shown) such as a liquid crystal cell. The surface of the pressure-sensitive adhesive layer 140 is usually protected by a release film (not shown).
　本発明者らは、偏光板の打ち抜き工程において、クラックや層間剥離が生じるメカニズムについて、以下のように推測した。 The present inventors speculated as follows about the mechanism by which cracks and delamination occur in the punching process of the polarizing plate.
　図２は、偏光板１００の打ち抜き工程における推定機構を説明する断面図である。このうち、図２Ａは、偏光板１００に刃１６０を押し込むときの断面図であり、図２Ｂは、偏光板１００から刃１６０を引き抜くときの断面図である。 FIG. 2 is a cross-sectional view illustrating an estimation mechanism in the punching process of the polarizing plate 100. Of these, FIG. 2A is a cross-sectional view when the blade 160 is pushed into the polarizing plate 100, and FIG. 2B is a cross-sectional view when the blade 160 is pulled out from the polarizing plate 100.
　図２Ａに示されるように、刃１６０を偏光板１００に押し込む際、保護フィルム１２０Ａは、刃１６０の押し込み時には、刃１６０の押し込みによって隣接する層が押し込まれないため、刃の押し込みによって生じる応力は小さいが（図２Ａの点線矢印）；保護フィルム１２０Ｂは、刃の押し込みによって隣接する層（接着剤層１３０Ｂ、偏光子１１０、接着剤層１３０Ａおよび保護フィルム１２０Ａ）が押し込まれるため、刃の押し込みによって生じる応力が大きくなりやすい（図２Ａの実線矢印）。それにより、保護フィルム１２０Ｂは、保護フィルム１２０Ａよりも、刃の押し込みによって物理的な変形が大きく、かつ広範囲で生じやすい。それにより、刃１６０を押し込む際には、保護フィルム１２０Ｂにクラックが発生しやすく、刃１６０を引き抜く際には、保護フィルム１２０Ｂと接着剤層１３０Ｂとの間で層間剥離が生じやすい。 As shown in FIG. 2A, when the blade 160 is pushed into the polarizing plate 100, the protective film 120A does not push the adjacent layer due to the pushing of the blade 160, so that the stress generated by the pushing of the blade is Although small (dotted arrow in FIG. 2A); the protective film 120B is pushed by the blade because the adjacent layers (adhesive layer 130B, polarizer 110, adhesive layer 130A and protective film 120A) are pushed by the blade. The generated stress tends to increase (solid line arrow in FIG. 2A). As a result, the protective film 120B is more physically deformed by pushing the blade than the protective film 120A, and is more likely to occur in a wide range. As a result, cracks are likely to occur in the protective film 120B when the blade 160 is pushed in, and delamination is likely to occur between the protective film 120B and the adhesive layer 130B when the blade 160 is pulled out.
　これに対して本発明者らは、特許文献１のように、偏光子の一方の面に配置される保護フィルムに含まれるゴム粒子の平均アスペクト比と、偏光子の他方の面に配置される保護フィルムに含まれるゴム粒子の平均アスペクト比とを同じにするのではなく；保護フィルム１２０Ｂに含まれるゴム粒子１５０ｂの平均アスペクト比を、保護フィルム１２０Ａに含まれるゴム粒子１５０ａの平均アスペクト比よりも高くすることで、クラックや層間剥離を抑制できることを見出した（図２Ａ参照）。 On the other hand, as in Patent Document 1, the present inventors have the average aspect ratio of the rubber particles contained in the protective film arranged on one surface of the polarizer and the arrangement on the other surface of the polarizer. Rather than making the average aspect ratio of the rubber particles contained in the protective film the same; the average aspect ratio of the rubber particles 150b contained in the protective film 120B is larger than the average aspect ratio of the rubber particles 150a contained in the protective film 120A. It was found that cracks and delamination can be suppressed by increasing the height (see FIG. 2A).
　具体的には、保護フィルム１２０Ｂに含まれるゴム粒子１５０ｂの平均アスペクト比を、１．２～３．０に調整する。それにより、保護フィルム１２０Ｂに含まれるゴム粒子１５０ｂは、刃１６０の押し込みによって生じる保護フィルム１２０Ｂの変形に良好に追従しうるため、応力を緩和することができ、クラックなどを生じにくくすることができる。特に、ゴム粒子１５０ｂの硬度が比較的高く（スチレン量が比較的多く）、かつゴム粒子１５０ｂの硬度（スチレン量）＞ゴム粒子１５０ａの硬度（スチレン量）とすることで、保護フィルムＢに応力がかかった際に、ゴム粒子１５０ｂが引き伸ばされることによるゴム粒子１５０ｂと（メタ）アクリル系樹脂との界面剥離を一層生じにくくしうるため、平均アスペクト比を上記範囲とすることによる効果が一層得られやすい。また、保護フィルム１２０Ｂにおいて、刃の押し込み時に生じる応力を少なくしうるため、押し込んだ刃を引き抜く際に、保護フィルム１２０Ｂと接着剤層１３０Ｂとの層間剥離も生じにくくしうる（図２Ｂ参照）。 Specifically, the average aspect ratio of the rubber particles 150b contained in the protective film 120B is adjusted to 1.2 to 3.0. As a result, the rubber particles 150b contained in the protective film 120B can satisfactorily follow the deformation of the protective film 120B caused by the pushing of the blade 160, so that the stress can be relaxed and cracks and the like can be less likely to occur. .. In particular, by setting the hardness of the rubber particles 150b to be relatively high (the amount of styrene is relatively large) and the hardness of the rubber particles 150b (the amount of styrene)> the hardness of the rubber particles 150a (the amount of styrene), the protective film B is stressed. Since the interfacial peeling between the rubber particles 150b and the (meth) acrylic resin due to the stretching of the rubber particles 150b can be made more difficult to occur when the rubber particles 150b are applied, the effect of setting the average aspect ratio within the above range is further obtained. Easy to get rid of. Further, in the protective film 120B, since the stress generated when the blade is pushed in can be reduced, delamination between the protective film 120B and the adhesive layer 130B can be less likely to occur when the pushed blade is pulled out (see FIG. 2B).
　さらに、本発明者らは、保護フィルム１２０Ｂに含まれる（メタ）アクリル系樹脂を、メタクリル酸メチルに由来する構造単位（Ｕ１）と、フェニルマレイミドに由来する構造単位（Ｕ２）と、アクリル酸アルキルエステルに由来する構造単位（Ｕ３）とを所定の比率で含む共重合体とすることで、脆性を悪化させることなく、刃１６０を引き抜く際の層間剥離を一層抑制しうることを見出した（図２Ｂ参照）。特に、フェニルマレイミドに由来する構造単位（Ｕ２）は、平面性が高く、適度な極性を有するため、平均アスペクト比が適度に高く、平面性を有するゴム粒子１５０ｂと間の親和性が高まりやすい。それにより、ゴム粒子１５０ｂとの界面剥離を抑制でき、それにより保護フィルム１２０Ｂと接着剤層１３０Ｂとの層間剥離を抑制することができる。 Furthermore, the present inventors have described the (meth) acrylic resin contained in the protective film 120B as a structural unit (U1) derived from methyl methacrylate, a structural unit (U2) derived from phenylmaleimide, and an alkyl acrylate. It has been found that by using a copolymer containing a structural unit (U3) derived from an ester in a predetermined ratio, delamination when the blade 160 is pulled out can be further suppressed without deteriorating brittleness (Fig.). See 2B). In particular, the structural unit (U2) derived from phenylmaleimide has high flatness and has an appropriate polarity, so that the average aspect ratio is moderately high and the affinity with the flat rubber particles 150b tends to increase. As a result, interfacial delamination with the rubber particles 150b can be suppressed, and thereby delamination between the protective film 120B and the adhesive layer 130B can be suppressed.
　以下、本実施の形態に係る偏光板の各構成要素について説明する。 Hereinafter, each component of the polarizing plate according to the present embodiment will be described.
　１－１．偏光子
　偏光子は、一定方向の偏波面の光だけを通す素子である。偏光子は、通常、ポリビニルアルコール系偏光フィルムでありうる。ポリビニルアルコール系偏光フィルムの例には、ポリビニルアルコール系フィルムにヨウ素を染色させたものや、二色性染料を染色させたものが含まれる。 1-1. Polarizer A polarizing element is an element that allows only light on a plane of polarization in a certain direction to pass through. The polarizer can usually be a polyvinyl alcohol-based polarizing film. Examples of the polyvinyl alcohol-based polarizing film include a polyvinyl alcohol-based film dyed with iodine and a film dyed with a dichroic dye.
　ポリビニルアルコール系偏光フィルムは、ポリビニルアルコール系フィルムを一軸延伸した後、ヨウ素または二色性染料で染色したフィルム（好ましくはさらにホウ素化合物で耐久性処理を施したフィルム）であってもよいし；ポリビニルアルコール系フィルムをヨウ素または二色性染料で染色した後、一軸延伸したフィルム（好ましくは、さらにホウ素化合物で耐久性処理を施したフィルム）であってもよい。偏光子１１０の吸収軸は、通常、最大延伸方向と平行である。 The polyvinyl alcohol-based polarizing film may be a film obtained by uniaxially stretching a polyvinyl alcohol-based film and then dyeing it with iodine or a bicolor dye (preferably a film further subjected to a durability treatment with a boron compound); polyvinyl. An alcohol-based film may be a film that has been dyed with iodine or a bicolor dye and then uniaxially stretched (preferably a film that has been further subjected to a durability treatment with a boron compound). The absorption axis of the polarizer 110 is usually parallel to the maximum stretching direction.
　ポリビニルアルコール系偏光フィルムとしては、例えば、特開２００３－２４８１２３号公報、特開２００３－３４２３２２号公報等に記載のエチレン単位の含有量１～４モル％、重合度２０００～４０００、けん化度９９．０～９９．９９モル％のエチレン変性ポリビニルアルコールが用いられる。 Examples of the polyvinyl alcohol-based polarizing film include the ethylene unit content of 1 to 4 mol%, the degree of polymerization of 2000 to 4000, and the degree of saponification of 99, which are described in JP-A-2003-248123 and JP-A-2003-342322. 0-99.99 mol% ethylene-modified polyvinyl alcohol is used.
　偏光子の厚みは、５～３０μｍであることが好ましく、偏光板を薄型化する観点などから、５～２０μｍであることがより好ましい。 The thickness of the polarizer is preferably 5 to 30 μm, and more preferably 5 to 20 μm from the viewpoint of thinning the polarizing plate.
　１－２．保護フィルムＡ
　保護フィルムＡは、（メタ）アクリル系樹脂と、ゴム粒子ａとを含む。 1-2. Protective film A
The protective film A contains a (meth) acrylic resin and rubber particles a.
　１－２－１．（メタ）アクリル系樹脂
　保護フィルムＡに含まれる（メタ）アクリル系樹脂は、メタクリル酸メチルに由来する構造単位を含む単独重合体であってもよいし、メタクリル酸メチルに由来する構造単位と、それと共重合可能なメタクリル酸メチル以外の共重合モノマーに由来する構造単位とを含む共重合体であってもよい。 1-2-1. (Meta) Acrylic Resin The (meth) acrylic resin contained in the protective film A may be a copolymer containing a structural unit derived from methyl methacrylate, or may be a copolymer containing a structural unit derived from methyl methacrylate and a structural unit derived from methyl methacrylate. It may be a copolymer containing a structural unit derived from a copolymerizable monomer other than methyl methacrylate which can be copolymerized with the copolymer.
　共重合モノマーは、特に制限されず、（メタ）アクリル酸エチル、（メタ）アクリル酸プロピル、六員環ラクトン（メタ）アクリル酸エステルなどの、メタクリル酸メチル以外のアルキル基の炭素数が１～１８の（メタ）アクリル酸エステル類；（メタ）アクリル酸などのα，β－不飽和酸；マレイン酸、フマル酸、イタコン酸などの不飽和基含有二価カルボン酸；スチレン、α－メチルスチレンなどの芳香族ビニル類；アクリロニトリル、メタクリロニトリルなどのα，β－不飽和ニトリル類；マレイミド、Ｎ－置換マレイミドなどのマレイミド類；無水マレイン酸、グルタル酸無水物が含まれる。共重合モノマーは、１種類で用いてもよいし、２種類以上を併用してもよい。 The copolymerization monomer is not particularly limited, and the alkyl group other than methyl methacrylate, such as ethyl (meth) acrylate, propyl (meth) acrylate, and six-membered ring lactone (meth) acrylic acid ester, has 1 to 1 to carbon atoms. 18 (meth) acrylic acid esters; α, β-unsaturated acids such as (meth) acrylic acid; unsaturated group-containing divalent carboxylic acids such as maleic anhydride, fumaric acid, itaconic acid; styrene, α-methylstyrene Aromatic vinyls such as; α, β-unsaturated nitriles such as acrylonitrile and methacrylonitrile; maleimides such as maleimide and N-substituted maleimide; maleic anhydride and glutaric anhydride are included. One type of copolymerization monomer may be used, or two or more types may be used in combination.
　中でも、フィルムの引張弾性率を後述する範囲に調整しやすい観点などから、メタクリル酸メチルに由来する構造単位を含む単独重合体（ポリメチルメタクリレート）または、メタクリル酸メチルに由来する構造単位と、グルタルイミド構造単位（例えば（メタ）アクリル酸エステルに由来する構造単位を、アミンなどのイミド化剤と反応させたものなど）、グルタル酸無水物に由来する構造単位、または六員環ラクトン（メタ）アクリル酸エステルに由来する構造単位（ラクトン環構造単位）とを含む共重合体であることが好ましく、メタクリル酸メチルに由来する構造単位を含む単独重合体（ポリメチルメタクリレート）がより好ましい。 Among them, from the viewpoint that the tensile elasticity of the film can be easily adjusted within the range described later, a homopolymer containing a structural unit derived from methyl methacrylate (polymethyl methacrylate) or a structural unit derived from methyl methacrylate and glutal. An imide structural unit (for example, a structural unit derived from (meth) acrylic acid ester reacted with an imidizing agent such as amine), a structural unit derived from glutaric anhydride, or a six-membered ring lactone (meth). It is preferably a copolymer containing a structural unit derived from an acrylic acid ester (lactone ring structural unit), and more preferably a homopolymer containing a structural unit derived from methyl methacrylate (polymethylmethacrylate).
　メタクリル酸メチルに由来する構造単位の含有量は、（メタ）アクリル系樹脂を構成する全構造単位に対して８０～１００質量％であることが好ましく、９０～１００質量％であることがより好ましい。（メタ）アクリル系樹脂のモノマーの種類や組成は、１Ｈ－ＮＭＲにより特定することができる。 The content of the structural unit derived from methyl methacrylate is preferably 80 to 100% by mass, more preferably 90 to 100% by mass, based on all the structural units constituting the (meth) acrylic resin. .. The type and composition of the (meth) acrylic resin monomer can be specified by 1 1 H-NMR.
　（メタ）アクリル系樹脂のガラス転移温度（Ｔｇ）は、９０℃以上であることが好ましく、１００～１５０℃であることがより好ましい。（メタ）アクリル系樹脂のＴｇが９０℃以上である保護フィルムＡは、良好な耐熱性を有しうる。 The glass transition temperature (Tg) of the (meth) acrylic resin is preferably 90 ° C. or higher, more preferably 100 to 150 ° C. The protective film A in which the Tg of the (meth) acrylic resin is 90 ° C. or higher can have good heat resistance.
　（メタ）アクリル系樹脂のガラス転移温度（Ｔｇ）は、ＤＳＣ（Ｄｉｆｆｅｒｅｎｔｉａｌ Ｓｃａｎｎｉｎｇ Ｃｏｌｏｒｉｍｅｔｒｙ：示差走査熱量法）を用いて、ＪＩＳ Ｋ ７１２１－２０１２またはＡＳＴＭ Ｄ ３４１８－８２に準拠して測定することができる。 The glass transition temperature (Tg) of the (meth) acrylic resin can be measured using DSC (Differential Scanning Colory) according to JIS K7121-2012 or ASTM D3418-82. ..
　（メタ）アクリル系樹脂の重量平均分子量（Ｍｗ）は、特に制限されず、製膜法に応じて、適宜設定されうる。例えば、保護フィルムＡがメルト法で製膜されたものである場合、（メタ）アクリル系樹脂の重量平均分子量は、１０万～３０万であることが好ましい。保護フィルムＡがキャスト法で製膜されたものである場合、（メタ）アクリル系樹脂の重量平均分子量は、５０万～３００万であることが好ましく、６０万～２００万であることがより好ましい。（メタ）アクリル系樹脂の重量平均分子量が上記範囲であると、製膜性を損なうことなく、フィルムに十分な機械的強度（靱性）を付与しうる。 The weight average molecular weight (Mw) of the (meth) acrylic resin is not particularly limited and can be appropriately set according to the film forming method. For example, when the protective film A is formed by a melting method, the weight average molecular weight of the (meth) acrylic resin is preferably 100,000 to 300,000. When the protective film A is formed by a casting method, the weight average molecular weight of the (meth) acrylic resin is preferably 500,000 to 3,000,000, more preferably 600,000 to 2,000,000. .. When the weight average molecular weight of the (meth) acrylic resin is in the above range, sufficient mechanical strength (toughness) can be imparted to the film without impairing the film-forming property.
　（メタ）アクリル系樹脂の重量平均分子量（Ｍｗ）は、ゲルパーミエーションクロマトグラフィー（ＧＰＣ）によりポリスチレン換算にて測定することができる。具体的には、東ソー社製 ＨＬＣ８２２０ＧＰＣ）、カラム（東ソー社製 ＴＳＫ－ＧＥＬ  Ｇ６０００ＨＸＬ－Ｇ５０００ＨＸＬ－Ｇ５０００ＨＸＬ－Ｇ４０００ＨＸＬ－Ｇ３０００ＨＸＬ 直列）を用いて測定することができる。測定条件は、後述する実施例と同様としうる。 The weight average molecular weight (Mw) of the (meth) acrylic resin can be measured in terms of polystyrene by gel permeation chromatography (GPC). Specifically, the measurement can be performed using a Tosoh company HLC8220GPC) and a column (Tosoh company TSK-GEL G6000HXL-G5000HXL-G5000HXL-G4000HXL-G3000HXL series). The measurement conditions may be the same as in the examples described later.
　（メタ）アクリル系樹脂の含有量は、保護フィルムＡに対して６０質量％以上であることが好ましく、７０質量％以上であることがより好ましい。 The content of the (meth) acrylic resin is preferably 60% by mass or more, and more preferably 70% by mass or more with respect to the protective film A.
　１－２－２．ゴム粒子ａ
　保護フィルムＡに含まれるゴム粒子ａは、保護フィルムＡに靱性や柔軟性を付与しうる。 1-2-2. Rubber particles a
The rubber particles a contained in the protective film A can impart toughness and flexibility to the protective film A.
　保護フィルムＡの厚み方向に沿った断面において、ゴム粒子ａの平均アスペクト比は、１．０～１．１であることが好ましい。偏光板の打ち抜き工程において、刃の押し込みによって保護フィルムＡに生じる応力は、刃の押し込みによって保護フィルムＢに生じる応力よりも小さいため、ゴム粒子ａの追従性の調整は、ゴム粒子ｂほどは必要ないからである。また、保護フィルムＡに刃が押し込まれた際に、応力がゴム粒子１５０ａに対して等方的にかかりやすいため、ゴム粒子１５０ａ自体で応力を発散させやすい。 The average aspect ratio of the rubber particles a is preferably 1.0 to 1.1 in the cross section of the protective film A along the thickness direction. In the punching process of the polarizing plate, the stress generated in the protective film A by pushing the blade is smaller than the stress generated in the protective film B by pushing the blade. Therefore, it is necessary to adjust the followability of the rubber particles a as much as the rubber particles b. Because there isn't. Further, when the blade is pushed into the protective film A, the stress is likely to be applied isotropically to the rubber particles 150a, so that the stress is easily dissipated by the rubber particles 150a itself.
　平均アスペクト比とは、複数のゴム粒子ａのアスペクト比の平均値を意味する。アスペクト比とは、ゴム粒子の長径の短径に対する比（長径／短径）を意味する。 The average aspect ratio means the average value of the aspect ratios of the plurality of rubber particles a. The aspect ratio means the ratio (major axis / minor axis) of the major axis of the rubber particles to the minor axis.
　保護フィルムＡの厚み方向に沿った断面において、ゴム粒子ａの長径は、ゴム粒子ａが外接する長方形の長手方向の長さ（長辺の長さ）として測定することができ；ゴム粒子ａの短径は、ゴム粒子ａが外接する長方形の短手方向の長さ（短辺の長さ）として測定することができる。 In the cross section along the thickness direction of the protective film A, the major axis of the rubber particles a can be measured as the length in the longitudinal direction (the length of the long side) of the rectangle circumscribing the rubber particles a; The minor axis can be measured as the length (the length of the short side) of the rectangle circumscribing the rubber particles a in the lateral direction.
　保護フィルムＡの厚み方向に沿った断面は、具体的には、保護フィルムＡの厚み方向に沿った断面のうち、面内遅相軸と平行な断面をいう。面内遅相軸とは、フィルム面において屈折率が最大となる軸をいう。保護フィルムＡの面内遅相軸を特定できない場合は、保護フィルムＡの厚み方向に沿った断面のうち、保護フィルムＡの幅方向（ＴＤ方向）と平行な断面をいう。 The cross section along the thickness direction of the protective film A specifically refers to a cross section along the thickness direction of the protective film A that is parallel to the in-plane slow phase axis. The in-plane slow-phase axis refers to the axis having the maximum refractive index on the film surface. When the in-plane slow-phase axis of the protective film A cannot be specified, it means a cross section parallel to the width direction (TD direction) of the protective film A among the cross sections along the thickness direction of the protective film A.
　ゴム粒子ａの平均長径は、１００～４００ｎｍであることが好ましい。ゴム粒子ａの平均長径が１００ｎｍ以上であると、フィルムに十分な靱性を付与しやすく、４００ｎｍ以下であると、フィルムの透明性が低下しにくい。ゴム粒子ａの平均長径は、１５０～３００ｎｍであることがより好ましい。ゴム粒子の平均長径は、ゴム粒子の長径の平均値である。 The average major axis of the rubber particles a is preferably 100 to 400 nm. When the average major axis of the rubber particles a is 100 nm or more, sufficient toughness is easily imparted to the film, and when it is 400 nm or less, the transparency of the film is unlikely to decrease. The average major axis of the rubber particles a is more preferably 150 to 300 nm. The average major axis of the rubber particles is the average value of the major axis of the rubber particles.
　ゴム粒子ａの平均アスペクト比と平均長径は、以下の方法で算出することができる。
　１）保護フィルムＡの断面をＴＥＭ観察する。観察領域は、保護フィルムＡの厚みに相当する領域としてもよいし、５μｍ×５μｍの領域としてもよい。保護フィルムＡの厚みに相当する領域を観察領域とする場合、測定箇所は１箇所としうる。５μｍ×５μｍの領域を観察領域とする場合、測定箇所は４箇所としうる。
　２）得られたＴＥＭ画像における各ゴム粒子の長径、短径を測定し、アスペクト比をそれぞれ算出する。複数のゴム粒子から得られたアスペクト比の平均値を「平均アスペクト比」とし、複数のゴム粒子から得られた長径の平均値を「平均長径」とする。 The average aspect ratio and the average major axis of the rubber particles a can be calculated by the following methods.
1) TEM observe the cross section of the protective film A. The observation region may be a region corresponding to the thickness of the protective film A, or a region of 5 μm × 5 μm. When the region corresponding to the thickness of the protective film A is used as the observation region, the number of measurement points may be one. When the area of 5 μm × 5 μm is used as the observation area, the number of measurement points may be four.
2) Measure the major axis and minor axis of each rubber particle in the obtained TEM image, and calculate the aspect ratio respectively. The average value of the aspect ratios obtained from the plurality of rubber particles is defined as the "average aspect ratio", and the average value of the major axes obtained from the plurality of rubber particles is defined as the "average major axis".
　ゴム粒子ａの平均アスペクト比や平均長径は、保護フィルムＡの製膜条件や延伸条件によって調整することができる。ゴム粒子ａの平均アスペクト比を小さくするためには、例えば保護フィルムの製膜時の延伸倍率を低くすること（好ましくは未延伸にすること）が好ましい。 The average aspect ratio and average major axis of the rubber particles a can be adjusted according to the film forming conditions and stretching conditions of the protective film A. In order to reduce the average aspect ratio of the rubber particles a, for example, it is preferable to reduce the stretching ratio of the protective film during film formation (preferably unstretched).
　そのようなゴム粒子ａは、ゴム状重合体（架橋重合体）を含む粒子である。ゴム状重合体の例には、ブタジエン系架橋重合体、（メタ）アクリル系架橋重合体、およびオルガノシロキサン系架橋重合体が含まれる。中でも、メタクリル系樹脂との屈折率差が小さく、保護フィルムの透明性が損なわれにくい観点では、（メタ）アクリル系架橋重合体が好ましく、アクリル系架橋重合体（アクリル系ゴム状重合体）がより好ましい。 Such rubber particles a are particles containing a rubber-like polymer (crosslinked polymer). Examples of rubber-like polymers include butadiene-based crosslinked polymers, (meth) acrylic-based crosslinked polymers, and organosiloxane-based crosslinked polymers. Among them, the (meth) acrylic crosslinked polymer is preferable, and the acrylic crosslinked polymer (acrylic rubber-like polymer) is preferable from the viewpoint that the difference in refractive index from the methacrylic resin is small and the transparency of the protective film is not easily impaired. More preferred.
　すなわち、ゴム粒子は、アクリル系ゴム状重合体（ａ１）を含む粒子であることが好ましい。 That is, the rubber particles are preferably particles containing the acrylic rubber-like polymer (a1).
　（アクリル系ゴム状重合体（ａ１））
　アクリル系ゴム状重合体（ａ１）は、アクリル酸エステルを主成分とする架橋重合体である。すなわち、アクリル系ゴム状重合体（ａ１）は、アクリル酸エステルに由来する構造単位と、それと共重合可能なモノマーに由来する構造単位と、１分子中に２以上のラジカル重合性基（非共役な反応性二重結合）を有する多官能性モノマーに由来する構造単位とを含む架橋重合体であることが好ましい。 (Acrylic rubber-like polymer (a1))
The acrylic rubber-like polymer (a1) is a crosslinked polymer containing an acrylic acid ester as a main component. That is, the acrylic rubber-like polymer (a1) has a structural unit derived from an acrylic acid ester, a structural unit derived from a monomer copolymerizable therewith, and two or more radically polymerizable groups (non-conjugated) in one molecule. It is preferably a crosslinked polymer containing a structural unit derived from a polyfunctional monomer having a reactive double bond.
　アクリル酸エステルは、アクリル酸メチル、アクリル酸ブチルなどのアルキル基の炭素数１～１２のアクリル酸アルキルエステルであることが好ましい。アクリル酸エステルは、１種類であってもよいし、２種類以上であってもよい。ゴム粒子のガラス転移温度を－１５℃以下にする観点では、アクリル酸エステルは、少なくとも、炭素数４～１０のアクリル酸アルキルエステルを含むことが好ましい。 The acrylic acid ester is preferably an acrylic acid alkyl ester having 1 to 12 carbon atoms of an alkyl group such as methyl acrylate and butyl acrylate. The acrylic ester may be one kind or two or more kinds. From the viewpoint of lowering the glass transition temperature of the rubber particles to −15 ° C. or lower, the acrylic acid ester preferably contains at least an acrylic acid alkyl ester having 4 to 10 carbon atoms.
　アクリル酸エステルに由来する構造単位の含有量は、アクリル系ゴム状重合体（ａ）を構成する全構造単位に対して４０～８０質量％であることが好ましく、４５～６５質量％であることがより好ましい。アクリル酸エステルの含有量が４５重量％以上であると、フィルムに十分な靱性を付与しやすい。 The content of the structural unit derived from the acrylic acid ester is preferably 40 to 80% by mass, preferably 45 to 65% by mass, based on all the structural units constituting the acrylic rubber-like polymer (a). Is more preferable. When the content of the acrylic acid ester is 45% by weight or more, it is easy to impart sufficient toughness to the film.
　共重合可能なモノマーは、アクリル酸エステルと共重合可能なモノマーのうち、多官能性モノマー以外のものである。すなわち、共重合可能なモノマーは、２以上のラジカル重合性基を有しない。共重合可能なモノマーの例には、メタクリル酸メチルなどのメタクリル酸エステル；スチレン、メチルスチレンなどのスチレン類；アクリロニトリル、メタクリロニトリルなどの不飽和ニトリル類などが含まれる。中でも、保護フィルムＡの引張弾性率を、保護フィルムＢの引張弾性率よりも低くしやすくする観点などから、共重合可能なモノマーは、スチレン類を含むことが好ましい。 The copolymerizable monomer is a monomer copolymerizable with the acrylic acid ester other than the polyfunctional monomer. That is, the copolymerizable monomer does not have two or more radically polymerizable groups. Examples of copolymerizable monomers include methacrylic acid esters such as methyl methacrylate; styrenes such as styrene and methylstyrene; unsaturated nitriles such as acrylonitrile and methacrylonitrile. Above all, from the viewpoint of making the tensile elastic modulus of the protective film A lower than the tensile elastic modulus of the protective film B, the copolymerizable monomer preferably contains styrenes.
　共重合可能なモノマーがスチレン類を含む場合、保護フィルムＡに含まれるゴム粒子ａのスチレン類に由来する構造単位の含有量は、保護フィルムＢに含まれるゴム粒子ｂのスチレン類に由来する構造単位の含有量よりも少ないことが好ましい。すなわち、アクリル系ゴム状重合体（ａ１）のスチレン類に由来する構造単位の含有量は、アクリル系ゴム状重合体（ｂ１）のスチレン類に由来する構造単位の含有量よりも少ないことが好ましい。具体的には、アクリル系ゴム状重合体（ａ１）のスチレン類に由来する構造単位の含有量は、アクリル系ゴム状重合体（ａ１）を構成する全構造単位に対して５～５５質量％であることが好ましく、３０～５０質量％であることがより好ましい。スチレン類に由来する構造単位の含有量が上記範囲内であると、ゴム粒子ａを適度な硬さに調整しやすい。 When the copolymerizable monomer contains styrenes, the content of the structural unit derived from the styrenes of the rubber particles a contained in the protective film A is the structure derived from the styrenes of the rubber particles b contained in the protective film B. It is preferably less than the content of the unit. That is, the content of the structural unit derived from the styrenes of the acrylic rubber-like polymer (a1) is preferably smaller than the content of the structural unit derived from the styrenes of the acrylic rubber-like polymer (b1). .. Specifically, the content of the structural unit derived from the styrenes of the acrylic rubber-like polymer (a1) is 5 to 55% by mass with respect to all the structural units constituting the acrylic rubber-like polymer (a1). It is preferably, and more preferably 30 to 50% by mass. When the content of the structural unit derived from styrenes is within the above range, the rubber particles a can be easily adjusted to an appropriate hardness.
　ゴム粒子のスチレン類に由来する構造単位の含有量は、熱分解ＧＣ／ＭＳにより検出されるピークの面積比から測定することができる。具体的には、以下の手順で測定することができる。
　１）まず、スチレン類の含有量が異なる既知の試料を幾つか準備し、熱分解ＧＣ／ＭＳ測定を行い、得られたピーク面積比に基づいて検量線を作成する。
　２）次いで、測定対象となる試料について、熱分解ＧＣ／ＭＳ測定を行い、ピーク面積比を算出する。
　３）上記２）で得られたピーク面積比を、上記１）の検量線と照合して、測定対象となる試料のスチレン類の含有量を特定する。
　ＧＣＭＳの測定条件は、以下の通りとしうる。
　測定装置：ＳＨＩＭＡＺＵ　ＧＣＭＳ　ＱＰ２０１０
　カラム種：Ｕｒｔｒａ　Ａｌｌｏｙ－５（サイズ３０ｍ×径０．２５ｍｍ）
　キャリアガス種：Ｈｅ
　流量条件：１．８ｍＬ／分
　カラムオーブン温度条件：４０℃－１０℃／分－３２０℃
　インターフェイス温度：３００℃
　イオン源温度：２００℃
　検出モード：ＳＩＭ（ターゲットイオン：ｍ／ｚ１０４、確認イオン：ｍ／ｚ７８） The content of the structural unit derived from styrenes of the rubber particles can be measured from the area ratio of the peak detected by the thermal decomposition GC / MS. Specifically, it can be measured by the following procedure.
1) First, some known samples having different styrene contents are prepared, pyrolysis GC / MS measurement is performed, and a calibration curve is prepared based on the obtained peak area ratio.
2) Next, pyrolysis GC / MS measurement is performed on the sample to be measured, and the peak area ratio is calculated.
3) The peak area ratio obtained in 2) above is collated with the calibration curve in 1) above to specify the content of styrenes in the sample to be measured.
The measurement conditions for GCMS can be as follows.
Measuring device: SHIMAZU GCMS QP2010
Column type: Ultra Alloy-5 (size 30 m x diameter 0.25 mm)
Carrier gas type: He
Flow rate condition: 1.8 mL / min Column oven temperature condition: 40 ° C-10 ° C / min-320 ° C
Interface temperature: 300 ° C
Ion source temperature: 200 ° C
Detection mode: SIM (target ion: m / z104, confirmed ion: m / z78)
　多官能性モノマーの例には、アリル（メタ）アクリレート、トリアリルシアヌレート、トリアリルイソシアヌレート、ジアリルフタレート、ジアリルマレート、ジビニルアジペート、ジビニルベンゼン、エチレングリコールジ（メタ）アクリレート、ジエチレングリコール（メタ）アクリレート、トリエチレングリコールジ（メタ）アクリレート、トリメチルロールプロパントリ（メタ）アクリレート、テトロメチロールメタンテトラ（メタ）アクリレート、ジプロピレングリコールジ（メタ）アクリレート、ポリエチレングリコールジ（メタ）アクリレートが含まれる。 Examples of polyfunctional monomers include allyl (meth) acrylate, triallyl cyanurate, triallyl isocyanurate, diallyl phthalate, diallyl malate, divinyl adipate, divinylbenzene, ethylene glycol di (meth) acrylate, and diethylene glycol (meth). Includes acrylates, triethylene glycol di (meth) acrylates, trimethyl roll propanthry (meth) acrylates, tetromethylol methanetetra (meth) acrylates, dipropylene glycol di (meth) acrylates, and polyethylene glycol di (meth) acrylates.
　多官能性モノマーに由来する構造単位の含有量は、アクリル系ゴム状重合体（ａ１）を構成する全構造単位に対して０．０５～１０質量％であることが好ましく、０．１～５質量％であることがより好ましい。多官能性モノマーの含有量が０．０５質量％以上であると、得られるアクリル系ゴム状重合体（ａ）の架橋度を高めやすいため、得られるフィルムの硬度、剛性が損なわれすぎず、１０質量％以下であると、フィルムの靱性が損なわれにくい。 The content of the structural unit derived from the polyfunctional monomer is preferably 0.05 to 10% by mass, preferably 0.1 to 5% by mass, based on all the structural units constituting the acrylic rubber-like polymer (a1). More preferably, it is by mass%. When the content of the polyfunctional monomer is 0.05% by mass or more, the degree of cross-linking of the obtained acrylic rubber-like polymer (a) is easily increased, so that the hardness and rigidity of the obtained film are not excessively impaired. When it is 10% by mass or less, the toughness of the film is not easily impaired.
　アクリル系ゴム状重合体（ａ１）を含む粒子は、アクリル系ゴム状重合体（ａ１）からなる粒子であってもよいし；アクリル系ゴム状重合体（ａ１）の存在下で、メタクリル酸エステルなどのモノマー混合物を少なくとも１段以上重合して得られるアクリル系グラフト共重合体からなる粒子、すなわち、アクリル系ゴム状重合体（ａ１）を含むコア部と、それを覆うシェル部とを有するコアシェル型の粒子であってもよい。 The particles containing the acrylic rubber-like polymer (a1) may be particles made of the acrylic rubber-like polymer (a1); in the presence of the acrylic rubber-like polymer (a1), a methacrylic acid ester. A core shell having particles composed of an acrylic graft copolymer obtained by polymerizing a mixture of monomers such as the above in at least one stage, that is, a core portion containing an acrylic rubber-like polymer (a1) and a shell portion covering the core portion. It may be a type of particle.
　コアシェル型の粒子を構成するコア部は、アクリル系ゴム状重合体（ａ１）を含む。コアシェル型の粒子を構成するシェル部は、メタクリル酸エステルに由来する構造単位を含む重合体（ａ２）（グラフト成分）を含む。 The core portion constituting the core-shell type particles contains an acrylic rubber-like polymer (a1). The shell portion constituting the core-shell type particles contains a polymer (a2) (graft component) containing a structural unit derived from a methacrylic acid ester.
　メタクリル酸エステルは、メタクリル酸メチルなどのアルキル基の炭素数１～１２のメタクリル酸アルキルエステルであることが好ましい。メタクリル酸エステルは、１種類であってもよいし、２種類以上であってもよい。 The methacrylic acid ester is preferably an alkyl methacrylate ester having 1 to 12 carbon atoms of an alkyl group such as methyl methacrylate. The methacrylic acid ester may be one kind or two or more kinds.
　メタクリル酸エステルの含有量は、重合体（ａ２）を構成する全構造単位に対して５０質量％以上であることが好ましい。メタクリル酸エステルの含有量が５０質量％以上であると、得られるフィルムの硬度、剛性を低下させにくくしうる。また、メチレンクロライドなどの溶媒との親和性を高める観点では、メタクリル酸エステルの含有量は、重合体を構成する全構造単位に対して７０質量％以上であることがより好ましい。 The content of the methacrylic acid ester is preferably 50% by mass or more with respect to all the structural units constituting the polymer (a2). When the content of the methacrylic acid ester is 50% by mass or more, it is possible to make it difficult to reduce the hardness and rigidity of the obtained film. Further, from the viewpoint of enhancing the affinity with a solvent such as methylene chloride, the content of the methacrylic acid ester is more preferably 70% by mass or more with respect to all the structural units constituting the polymer.
　重合体（ａ２）は、共重合可能な他のモノマーに由来する構造単位をさらに含んでもよい。他のモノマーの例には、アクリル酸メチル、アクリル酸エチル、アクリル酸ｎ－ブチルなどのアクリル酸エステル；（メタ）アクリル酸ベンジル、（メタ）アクリル酸ジシクロペンタニル、（メタ）アクリル酸フェノキシエチルなどの脂環式構造、複素環式構造または芳香族基を有する（メタ）アクリル系モノマー類（環構造含有（メタ）アクリル系モノマー）が含まれる。 The polymer (a2) may further contain structural units derived from other copolymerizable monomers. Examples of other monomers are acrylic acid esters such as methyl acrylate, ethyl acrylate, n-butyl acrylate; benzyl (meth) acrylate, dicyclopentanyl (meth) acrylate, phenoxy (meth) acrylate. Includes (meth) acrylic monomers having an alicyclic structure such as ethyl, a heterocyclic structure or an aromatic group (ring structure-containing (meth) acrylic monomer).
　ゴム粒子におけるグラフト成分の重量比率（グラフト率）は、１０～２５０％であることが好ましく、２５～２００％であることがより好ましく、４０～２００％であることがより好ましく、６０～１５０％であることがさらに好ましい。上記質量比が１０％以上であると、シェル部の割合が少なくなりすぎないため、フィルムの硬度や剛性が損なわれにくい。上記質量比が２５０％以下であると、コア部の割合が少なくなりすぎないため、フィルムの靱性や脆性改善効果が損なわれにくい。 The weight ratio (graft ratio) of the graft component in the rubber particles is preferably 10 to 250%, more preferably 25 to 200%, more preferably 40 to 200%, and 60 to 150%. Is more preferable. When the mass ratio is 10% or more, the proportion of the shell portion is not too small, so that the hardness and rigidity of the film are not easily impaired. When the mass ratio is 250% or less, the proportion of the core portion is not too small, so that the toughness and brittleness improving effect of the film are not easily impaired.
　グラフト率の質量比率は、以下の方法で測定される。
　１）コアシェル型の粒子２ｇを、メチルエチルケトン５０ｍｌに溶解させ、遠心分離機（日立工機（株）製、ＣＰ６０Ｅ）を用い、回転数３００００ｒｐｍ、温度１２℃にて１時間遠心し、不溶分と可溶分とに分離する（遠心分離作業を合計３回セット）。
　２）得られた不溶分の重量を下記式に当てはめて、グラフト率を算出する。
　グラフト率（％）＝［｛（メチルエチルケトン不溶分の重量）－（アクリル系ゴム状重合体（ａ）の重量）｝／（アクリル系ゴム状重合体（ａ）の重量）］×１００ The mass ratio of the graft ratio is measured by the following method.
1) Dissolve 2 g of core-shell type particles in 50 ml of methyl ethyl ketone and centrifuge at a rotation speed of 30,000 rpm and a temperature of 12 ° C. for 1 hour using a centrifuge (manufactured by Hitachi Koki Co., Ltd., CP60E) to make it insoluble. Separate into the dissolved components (centrifugal separation work is set 3 times in total).
2) The graft ratio is calculated by applying the weight of the obtained insoluble matter to the following formula.
Graft ratio (%) = [{(weight of methyl ethyl ketone insoluble matter)-(weight of acrylic rubber-like polymer (a))} / (weight of acrylic rubber-like polymer (a))] × 100
　（物性について）
　ゴム粒子のガラス転移温度（Ｔｇ）は、室温以下（２５℃以下）でありうる。また、ゴム粒子ａのガラス転移温度は、ゴム粒子ｂのガラス転移温度よりも低いことが好ましい。ゴム粒子のガラス転移温度（Ｔｇ）が上記範囲を満たすと、フィルムに十分な靱性を付与しやすい。ゴム粒子のガラス転移温度（Ｔｇ）は、前述と同様の方法で測定される。 (About physical properties)
The glass transition temperature (Tg) of the rubber particles can be room temperature or lower (25 ° C. or lower). Further, the glass transition temperature of the rubber particles a is preferably lower than the glass transition temperature of the rubber particles b. When the glass transition temperature (Tg) of the rubber particles satisfies the above range, it is easy to impart sufficient toughness to the film. The glass transition temperature (Tg) of the rubber particles is measured by the same method as described above.
　ゴム粒子ａのガラス転移温度（Ｔｇ）は、例えばコア部やシェル部を構成する重合体の組成やグラフト率によって調整することができる。ゴム粒子のガラス転移温度（Ｔｇ）を低くするためには、後述するように、例えばコア部のアクリル系ゴム状重合体（ａ１）中の、アルキル基の炭素原子数が４以上のアクリル酸エステル／共重合可能なモノマーの質量比を多くする（例えば３以上、好ましくは４以上１０以下とする）ことが好ましい。 The glass transition temperature (Tg) of the rubber particles a can be adjusted, for example, by adjusting the composition and graft ratio of the polymers constituting the core portion and the shell portion. In order to lower the glass transition temperature (Tg) of the rubber particles, for example, an acrylic acid ester having an alkyl group having 4 or more carbon atoms in the acrylic rubber-like polymer (a1) in the core portion, as described later. / It is preferable to increase the mass ratio of the copolymerizable monomer (for example, 3 or more, preferably 4 or more and 10 or less).
　保護フィルムＡにおけるゴム粒子ａの含有量は、特に限定されないが、保護フィルムＢにおけるゴム粒子ｂの含有量よりも多いことが好ましい。具体的には、保護フィルムＡにおける、ゴム粒子ａの含有量は、保護フィルムＡに対して１２～２５質量％であることが好ましく、１５～２２質量％であることがより好ましい。ゴム粒子の含有量が１２質量％以上であると、保護フィルムＡに十分な靱性または柔軟性を付与しやすく、２５質量％以下であると、内部ヘイズの増大を抑制しやすい。 The content of the rubber particles a in the protective film A is not particularly limited, but is preferably higher than the content of the rubber particles b in the protective film B. Specifically, the content of the rubber particles a in the protective film A is preferably 12 to 25% by mass, more preferably 15 to 22% by mass with respect to the protective film A. When the content of the rubber particles is 12% by mass or more, it is easy to impart sufficient toughness or flexibility to the protective film A, and when it is 25% by mass or less, it is easy to suppress an increase in internal haze.
　１－２－３．他の成分
　保護フィルムＡは、必要に応じて上記以外の他の成分をさらに含んでもよい。他の成分の例には、マット剤などが含まれる。マット剤の例には、シリカ粒子などの無機微粒子、ガラス転移温度が８０℃以上の有機微粒子などが含まれる。 1-2-3. Other components The protective film A may further contain components other than the above, if necessary. Examples of other ingredients include matting agents and the like. Examples of the matting agent include inorganic fine particles such as silica particles and organic fine particles having a glass transition temperature of 80 ° C. or higher.
　１－２－４．物性
　（引張弾性率）
　保護フィルムＡの引張弾性率は、特に限定されないが、偏光板を打ち抜く際のクラックや層間剥離を抑制しやすくする観点では、保護フィルムＢの引張弾性率よりも低いことが好ましい。前述の通り、偏光板の打ち抜き工程において、刃の押し込みによって保護フィルムＡに生じる応力は、保護フィルムＢに生じる応力よりも小さいため、保護フィルムＡのゴム粒子ａにかかる負荷の調整は、保護フィルムＢほどは必要ではないからである。また、保護フィルムＡの引張弾性率が相対的に低いと、保護フィルムＢが受ける「刃の先端による応力」や「保護フィルムＡが押し込まれることによって生じる応力」を少なくすることもできる。具体的には、保護フィルムＡの２５℃における引張弾性率は、１．６～２．６ＧＰａであることが好ましい。 1-2-4. Physical properties (tensile modulus)
The tensile elastic modulus of the protective film A is not particularly limited, but is preferably lower than the tensile elastic modulus of the protective film B from the viewpoint of facilitating suppression of cracks and delamination when punching the polarizing plate. As described above, in the punching process of the polarizing plate, the stress generated in the protective film A by pushing the blade is smaller than the stress generated in the protective film B. Therefore, the load applied to the rubber particles a of the protective film A can be adjusted by adjusting the protective film. This is because it is not as necessary as B. Further, when the tensile elastic modulus of the protective film A is relatively low, it is possible to reduce the "stress caused by the tip of the blade" and the "stress generated by pushing the protective film A" received by the protective film B. Specifically, the tensile elastic modulus of the protective film A at 25 ° C. is preferably 1.6 to 2.6 GPa.
　保護フィルムＡの引張弾性率は、ＪＩＳ　Ｋ７１２７に準拠して測定することができる。具体的には、以下の手順で測定することができる。
　１）保護フィルムＡを、１ｃｍ（ＴＤ方向）×１０ｃｍ（ＭＤ方向）に切り出して試料片とし、２５℃６０％ＲＨの環境下で、２４時間調湿する。
　２）得られた試料片の引張弾性率を、ＪＩＳ　Ｋ７１２７に記載の引張試験方法により測定する。すなわち、試料片を、引張試験装置オリエンテック社製テンシロンにセットし、チャック間距離５０．０ｍｍ、引張り速度５０ｍｍ／ｍｉｎの条件で引張試験を行ったときの引張弾性率を測定する。測定は、２５℃、６０％ＲＨ下で行う。 The tensile elastic modulus of the protective film A can be measured according to JIS K7127. Specifically, it can be measured by the following procedure.
1) The protective film A is cut into 1 cm (TD direction) × 10 cm (MD direction) to prepare a sample piece, and the humidity is adjusted for 24 hours in an environment of 25 ° C. and 60% RH.
2) The tensile elasticity of the obtained sample piece is measured by the tensile test method described in JIS K7127. That is, the sample piece is set in the Tensilon manufactured by Orientec Co., Ltd., and the tensile elastic modulus is measured when the tensile test is performed under the conditions of a distance between chucks of 50.0 mm and a tensile speed of 50 mm / min. The measurement is performed at 25 ° C. and 60% RH.
　保護フィルムＡの引張弾性率は、（メタ）アクリル系樹脂の組成やゴム粒子ａの含有量および組成などによって調整されうる。保護フィルムＡの引張弾性率を低くする観点では、（メタ）アクリル系樹脂の環含有モノマー由来の構造単位の比率を低くしたり、ゴム粒子ａの含有量を多くしたり、ゴム粒子ａのスチレン類に由来する構造単位の含有量を少なくしたりすることが好ましい。 The tensile elastic modulus of the protective film A can be adjusted by the composition of the (meth) acrylic resin, the content and composition of the rubber particles a, and the like. From the viewpoint of lowering the tensile elastic modulus of the protective film A, the ratio of structural units derived from the ring-containing monomer of the (meth) acrylic resin may be lowered, the content of the rubber particles a may be increased, or the styrene of the rubber particles a may be increased. It is preferable to reduce the content of structural units derived from the class.
　（ヘイズ）
　保護フィルムＡは、透明性が高いことが好ましい。保護フィルムＡのヘイズは、２．０％以下であることが好ましく、１．０％以下であることがより好ましい。ヘイズは、試料４０ｍｍ×８０ｎｍを２５℃、６０％ＲＨでヘイズメーター（ＨＧＭ－２ＤＰ、スガ試験機）でＪＩＳＫ－６７１４に従って測定することができる。 (Haze)
The protective film A preferably has high transparency. The haze of the protective film A is preferably 2.0% or less, and more preferably 1.0% or less. Haze can be measured in accordance with JIS K-6714 with a haze meter (HGM-2DP, Suga Test Instruments) at 25 ° C. and 60% RH for a sample of 40 mm × 80 nm.
　（厚み）
　保護フィルムＡの厚みは、特に限定されないが、保護フィルムＢの厚みよりも厚いことが好ましい。保護フィルムＡの厚みが相対的に厚いと、保護フィルムＡの剛性が高まるため、偏光板の打ち抜き工程において、刃を抜く際に、保護フィルムＡだけでなく、偏光板全体の変形を少なくしやすい。具体的には、保護フィルムＡの厚みは、４０～１００μｍであることが好ましく、５０～８０μｍであることがより好ましい。 (Thickness)
The thickness of the protective film A is not particularly limited, but is preferably thicker than the thickness of the protective film B. When the protective film A is relatively thick, the rigidity of the protective film A is increased. Therefore, in the punching process of the polarizing plate, it is easy to reduce the deformation of not only the protective film A but also the entire polarizing plate when the blade is punched. .. Specifically, the thickness of the protective film A is preferably 40 to 100 μm, more preferably 50 to 80 μm.
　１－３．保護フィルムＢ
　保護フィルムＢは、表示装置にしたときに、偏光子と、液晶セルなどの表示素子との間に配置される位相差フィルムとして機能しうる。保護フィルムＢは、（メタ）アクリル系樹脂と、ゴム粒子ｂとを含む。 1-3. Protective film B
The protective film B can function as a retardation film arranged between a polarizing element and a display element such as a liquid crystal cell when used as a display device. The protective film B contains a (meth) acrylic resin and rubber particles b.
　１－３－１．（メタ）アクリル系樹脂
　保護フィルムＢに含まれる（メタ）アクリル系樹脂は、メタクリル酸メチルに由来する構造単位（Ｕ１）と、フェニルマレイミドに由来する構造単位（Ｕ２）と、アクリル酸アルキルエステルに由来する構造単位（Ｕ３）とを含む共重合体である。 1-3-1. (Meta) Acrylic Resin The (meth) acrylic resin contained in the protective film B is composed of a structural unit (U1) derived from methyl methacrylate, a structural unit (U2) derived from phenylmaleimide, and an acrylic acid alkyl ester. It is a copolymer containing the derived structural unit (U3).
　メタクリル酸メチルに由来する構造単位（Ｕ１）の含有量は、（メタ）アクリル系樹脂を構成する全構造単位に対して５０～９５質量％であることが好ましく、７０～９０質量％であることがより好ましい。 The content of the structural unit (U1) derived from methyl methacrylate is preferably 50 to 95% by mass, preferably 70 to 90% by mass, based on all the structural units constituting the (meth) acrylic resin. Is more preferable.
　フェニルマレイミドに由来する構造単位（Ｕ２）は、平面性が高い構造を有し、かつ適度な極性を有する。それにより、打抜き時に生じるフィルム面内の変形に対し、当該構造とゴム粒子との相互作用により、ゴム粒子と樹脂間に空隙が生じるのを抑制しやすい。その結果、（メタ）アクリル系樹脂とゴム粒子との界面剥離を抑制しやすく、それにより、保護フィルムＢと接着剤層との層間剥離も抑制しうる。 The structural unit (U2) derived from phenylmaleimide has a structure with high flatness and has an appropriate polarity. As a result, it is easy to suppress the formation of voids between the rubber particles and the resin due to the interaction between the structure and the rubber particles against the deformation in the film surface that occurs during punching. As a result, it is easy to suppress the interfacial delamination between the (meth) acrylic resin and the rubber particles, and thereby the delamination between the protective film B and the adhesive layer can also be suppressed.
　フェニルマレイミドに由来する構造単位（Ｕ２）の含有量は、（メタ）アクリル系樹脂を構成する全構造単位に対して１～２５質量％であることが好ましい。フェニルマレイミドに由来する構造単位（Ｕ２）の含有量が１質量％以上であると、ゴム粒子ｂと（メタ）アクリル系樹脂との界面剥離を抑制しやすく、それにより、保護フィルムＢと接着剤層との層間剥離を抑制しやすい。フェニルマレイミドに由来する構造単位（Ｕ２）の含有量が２５質量％以下であると、保護フィルムＢの脆性が損なわれにくい。フェニルマレイミドに由来する構造単位（Ｕ２）の含有量は、上記観点から、７～１５質量％であることがより好ましい。 The content of the structural unit (U2) derived from phenylmaleimide is preferably 1 to 25% by mass with respect to all the structural units constituting the (meth) acrylic resin. When the content of the structural unit (U2) derived from phenylmaleimide is 1% by mass or more, it is easy to suppress the interfacial peeling between the rubber particles b and the (meth) acrylic resin, whereby the protective film B and the adhesive It is easy to suppress delamination with the layer. When the content of the structural unit (U2) derived from phenylmaleimide is 25% by mass or less, the brittleness of the protective film B is not easily impaired. From the above viewpoint, the content of the structural unit (U2) derived from phenylmaleimide is more preferably 7 to 15% by mass.
　アクリル酸アルキルエステルに由来する構造単位（Ｕ３）は、（メタ）アクリル系樹脂とゴム粒子ｂとの界面剥離を抑制しうる。具体的には、後述するようにゴム粒子ｂのシェル部を構成する重合体（ｂ２）がアクリル酸ブチルなどのアクリル酸エステルに由来する構造単位を有する場合、アクリル酸アルキルエステルに由来する構造単位（Ｕ３）は、アクリル酸エステルに由来する構造単位との親和性が高いため、（メタ）アクリル系樹脂とゴム粒子ｂとの親和性を高めうる。それにより、偏光板の打ち抜き性において、（メタ）アクリル系樹脂とゴム粒子との間の界面剥離を抑制し、それにより保護フィルムＢと接着剤層との層間密着性の低下を抑制しうる。アクリル酸アルキルエステルは、アルキル部分の炭素原子数が１～７、好ましくは１～５のアクリル酸アルキルエステルであることが好ましい。アクリル酸アルキルエステルの例には、アクリル酸メチル、アクリル酸エチル、アクリル酸プロピル、アクリル酸ブチル、アクリル酸２－ヒドロキシエチル、アクリル酸ヘキシル、アクリル酸２－エチルヘキシルなどが含まれる。 The structural unit (U3) derived from the acrylic acid alkyl ester can suppress the interfacial peeling between the (meth) acrylic resin and the rubber particles b. Specifically, when the polymer (b2) constituting the shell portion of the rubber particles b has a structural unit derived from an acrylic acid ester such as butyl acrylate, as will be described later, a structural unit derived from the acrylic acid alkyl ester. Since (U3) has a high affinity with the structural unit derived from the acrylic acid ester, the affinity between the (meth) acrylic resin and the rubber particles b can be enhanced. As a result, in the punching property of the polarizing plate, the interfacial peeling between the (meth) acrylic resin and the rubber particles can be suppressed, thereby suppressing the deterioration of the interlayer adhesion between the protective film B and the adhesive layer. The acrylic acid alkyl ester is preferably an acrylic acid alkyl ester having an alkyl moiety having 1 to 7 carbon atoms, preferably 1 to 5 carbon atoms. Examples of alkyl acrylates include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-hydroxyethyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate and the like.
　アクリル酸アルキルエステルに由来する構造単位（Ｕ３）の含有量は、（メタ）アクリル系樹脂を構成する全構造単位に対して１～２５質量％であることが好ましい。アクリル酸アルキルエステルに由来する構造単位（Ｕ３）の含有量が１質量％以上であると、（メタ）アクリル系樹脂とゴム粒子との界面剥離を抑制しやすく、２５質量％以下であると、耐熱性が損なわれにくい。アクリル酸アルキルエステルに由来する構造単位の含有量は、上記観点から、５～１５質量％であることがより好ましい。 The content of the structural unit (U3) derived from the acrylic acid alkyl ester is preferably 1 to 25% by mass with respect to all the structural units constituting the (meth) acrylic resin. When the content of the structural unit (U3) derived from the acrylic acid alkyl ester is 1% by mass or more, it is easy to suppress the interfacial peeling between the (meth) acrylic resin and the rubber particles, and when it is 25% by mass or less, Heat resistance is not easily impaired. From the above viewpoint, the content of the structural unit derived from the acrylic acid alkyl ester is more preferably 5 to 15% by mass.
　フェニルマレイミドに由来する構造単位（Ｕ２）の、フェニルマレイミドに由来する構造単位（Ｕ２）とアクリル酸アルキルエステルに由来する構造単位（Ｕ３）の合計量に対する比率は、２０～７０質量％であることが好ましい。当該比率が２０質量％以上であると、保護フィルムＢの耐熱性や引張弾性率を適度に高めつつ、ゴム粒子ｂと樹脂との界面剥離やそれによる保護フィルムＢと接着剤層との層間剥離を十分に抑制しやすく、７０質量％以下であると、保護フィルムＢが脆くなりすぎない。 The ratio of the structural unit (U2) derived from phenylmaleimide to the total amount of the structural unit (U2) derived from phenylmaleimide and the structural unit (U3) derived from the acrylic acid alkyl ester shall be 20 to 70% by mass. Is preferable. When the ratio is 20% by mass or more, the heat resistance and tensile elastic modulus of the protective film B are appropriately increased, and the interfacial peeling between the rubber particles b and the resin and the delamination between the protective film B and the adhesive layer are caused. When it is 70% by mass or less, the protective film B does not become too brittle.
　（メタ）アクリル系樹脂は、必要に応じて上記以外の他のモノマーに由来する構造単位をさらに含んでもよい。そのような他のモノマーの例には、保護フィルムＡで用いられる（メタ）アクリル系樹脂を構成する共重合モノマーとして挙げたものと同様のものが含まれる。 The (meth) acrylic resin may further contain structural units derived from monomers other than the above, if necessary. Examples of such other monomers include those similar to those listed as the copolymerization monomers constituting the (meth) acrylic resin used in the protective film A.
　（メタ）アクリル系樹脂のガラス転移温度（Ｔｇ）は、１０５℃以上であることが好ましく、１１０～１５０℃であることがより好ましい。（メタ）アクリル系樹脂のＴｇが上記範囲内にあると、保護フィルムＢの耐熱性を高めやすいだけでなく、キャスト製膜時の乾燥効率を高めやすい。（メタ）アクリル系樹脂のＴｇを高めるためには、例えばフェニルマレイミドに由来する構造単位（Ｕ２）やアクリル酸アルキルエステルに由来する構造単位（Ｕ３）の含有量を適度に多くすることが好ましい。 The glass transition temperature (Tg) of the (meth) acrylic resin is preferably 105 ° C. or higher, more preferably 110 to 150 ° C. When the Tg of the (meth) acrylic resin is within the above range, not only the heat resistance of the protective film B can be easily increased, but also the drying efficiency during cast film formation can be easily increased. In order to increase the Tg of the (meth) acrylic resin, for example, it is preferable to appropriately increase the content of the structural unit (U2) derived from phenylmaleimide and the structural unit (U3) derived from the acrylic acid alkyl ester.
　（メタ）アクリル系樹脂の重量平均分子量（Ｍｗ）は、５０万～３００万であることが好ましい。（メタ）アクリル系樹脂の重量平均分子量が上記範囲であると、フィルムに十分な機械的強度（靱性）を付与しうる。（メタ）アクリル系樹脂の重量平均分子量は、上記観点から、６０万～２００万であることがより好ましい。 The weight average molecular weight (Mw) of the (meth) acrylic resin is preferably 500,000 to 3,000,000. When the weight average molecular weight of the (meth) acrylic resin is in the above range, sufficient mechanical strength (toughness) can be imparted to the film. From the above viewpoint, the weight average molecular weight of the (meth) acrylic resin is more preferably 600,000 to 2,000,000.
　（メタ）アクリル系樹脂の含有量は、保護フィルムＢに対して６０質量％以上であることが好ましく、７０質量％以上であることがより好ましい。 The content of the (meth) acrylic resin is preferably 60% by mass or more, and more preferably 70% by mass or more with respect to the protective film B.
　１－３－２．ゴム粒子ｂ
　保護フィルムＢに含まれるゴム粒子ｂは、前述と同様に、保護フィルムＢに靱性を付与しうる。 1-3-2. Rubber particles b
The rubber particles b contained in the protective film B can impart toughness to the protective film B in the same manner as described above.
　保護フィルムＢの厚み方向に沿った断面において、ゴム粒子ｂの平均アスペクト比は、１．２～３．０であることが好ましい。ゴム粒子ｂの平均アスペクト比が１．２以上であると、偏光板の打ち抜き工程において、ゴム粒子ｂが、刃が押し込まれたときの保護フィルムＢの変形に追従しやすい。そのため、保護フィルムＢが受ける応力を緩和することができ、偏光板の打ち抜き時のクラックなどを抑制しうる。ゴム粒子ｂの平均アスペクト比が３．０以下であると、ゴム粒子ｂと（メタ）アクリル系樹脂との界面剥離を生じにくくしうる。すなわち、ゴム粒子ｂの平均アスペクト比が高すぎると、ゴム粒子ｂの延伸による残留応力も大きいため、（メタ）アクリル系樹脂の塑性変形とゴム粒子ｂの塑性変形とにズレが生じやすく、（メタ）アクリル系樹脂とゴム粒子ｂとの界面に空隙を生じやすい。ゴム粒子ｂの平均アスペクト比が３．０以下であると、そのような延伸に起因する残留応力を少なくできるため、ゴム粒子ｂと（メタ）アクリル系樹脂との界面剥離を生じにくくしうる。それにより、偏光板の打ち抜き工程において押し込んだ刃を抜く際に、接着剤層と保護フィルムＢとの層間剥離を抑制することができる。ゴム粒子ｂの平均アスペクト比は、同様の観点から、１．５～２．９であることがより好ましい。 The average aspect ratio of the rubber particles b is preferably 1.2 to 3.0 in the cross section of the protective film B along the thickness direction. When the average aspect ratio of the rubber particles b is 1.2 or more, the rubber particles b tend to follow the deformation of the protective film B when the blade is pushed in in the punching step of the polarizing plate. Therefore, the stress received by the protective film B can be relaxed, and cracks and the like during punching of the polarizing plate can be suppressed. When the average aspect ratio of the rubber particles b is 3.0 or less, interfacial peeling between the rubber particles b and the (meth) acrylic resin can be less likely to occur. That is, if the average aspect ratio of the rubber particles b is too high, the residual stress due to the stretching of the rubber particles b is also large, so that the plastic deformation of the (meth) acrylic resin and the plastic deformation of the rubber particles b are likely to deviate from each other. Meta) Voids are likely to be formed at the interface between the acrylic resin and the rubber particles b. When the average aspect ratio of the rubber particles b is 3.0 or less, the residual stress caused by such stretching can be reduced, so that interfacial peeling between the rubber particles b and the (meth) acrylic resin can be less likely to occur. As a result, delamination between the adhesive layer and the protective film B can be suppressed when the blade pushed in in the punching step of the polarizing plate is pulled out. From the same viewpoint, the average aspect ratio of the rubber particles b is more preferably 1.5 to 2.9.
　ゴム粒子ｂの平均長径は、２５０～４００ｎｍであることが好ましい。ゴム粒子ａの平均長径が２５０ｎｍ以上であると、保護フィルムＢに十分な靱性や柔軟性を付与しうるだけでなく、応力を緩和させる効果が得られやすい。ゴム粒子ａの平均長径が４００ｎｍ以下であると、応力を分散させる効果が損なわれにくい。ゴム粒子ｂの平均長径は、ゴム粒子の長径の平均値である。 The average major axis of the rubber particles b is preferably 250 to 400 nm. When the average major axis of the rubber particles a is 250 nm or more, not only sufficient toughness and flexibility can be imparted to the protective film B, but also the effect of relaxing stress can be easily obtained. When the average major axis of the rubber particles a is 400 nm or less, the effect of dispersing stress is not easily impaired. The average major axis of the rubber particles b is the average value of the major axis of the rubber particles.
　ゴム粒子ｂの平均アスペクト比は、ゴム粒子ａの平均アスペクト比と同様に定義され、かつ同様の方法で測定することができる。ゴム粒子ｂの平均長径も、ゴム粒子ａの平均長径と同様に定義され、かつ同様の方法で測定することができる。 The average aspect ratio of the rubber particles b is defined in the same manner as the average aspect ratio of the rubber particles a, and can be measured by the same method. The average major axis of the rubber particles b is defined in the same manner as the average major axis of the rubber particles a, and can be measured by the same method.
　ゴム粒子ｂの平均アスペクト比および平均長径は、前述と同様に、保護フィルムＢの延伸条件によって調整することができる。ゴム粒子ｂの平均アスペクト比を大きくするためには、例えば保護フィルムＢの製膜時の延伸倍率を高くすることが好ましい。また、ゴム粒子ｂの平均長径を大きくするためには、例えば平均粒子径が大きいゴム粒子を原料として使用したり、延伸倍率を高くしたりすることが好ましい。 The average aspect ratio and average major axis of the rubber particles b can be adjusted according to the stretching conditions of the protective film B in the same manner as described above. In order to increase the average aspect ratio of the rubber particles b, for example, it is preferable to increase the stretching ratio of the protective film B during film formation. Further, in order to increase the average major axis of the rubber particles b, for example, it is preferable to use rubber particles having a large average particle size as a raw material or to increase the draw ratio.
　ゴム粒子ｂを構成するモノマー成分および構造は、ゴム粒子ａを構成するモノマー成分および構造と同様でありうる。例えば、ゴム粒子ｂは、アクリル系ゴム状重合体（ｂ１）を含むコア部と、メタクリル酸エステルに由来する構造単位を含む重合体（ｂ２）を含むシェル部とを有するコアシェル型の粒子でありうる。アクリル系ゴム状重合体（ｂ１）は、アクリル系ゴム状重合体（ａ１）と同様であり、組成は同じであってもよいし、異なってもよい。重合体（ｂ２）は、重合体（ａ２）と同様であり、組成は同じであってもよいし、異なってもよい。 The monomer component and structure constituting the rubber particle b may be the same as the monomer component and structure constituting the rubber particle a. For example, the rubber particles b are core-shell type particles having a core portion containing an acrylic rubber-like polymer (b1) and a shell portion containing a polymer (b2) containing a structural unit derived from a methacrylic acid ester. sell. The acrylic rubber-like polymer (b1) is the same as the acrylic rubber-like polymer (a1), and the composition may be the same or different. The polymer (b2) is the same as the polymer (a2), and the composition may be the same or different.
　ただし、ゴム粒子ｂを構成するアクリル系ゴム状重合体（ｂ１）がスチレン類に由来する構造単位を含む場合、保護フィルムＢに含まれるゴム粒子ｂのスチレン類に由来する構造単位の含有量は、保護フィルムＡに含まれるゴム粒子ａのスチレン類に由来する構造単位の含有量よりも多いことが好ましい。すなわち、アクリル系ゴム状重合体（ｂ１）のスチレン類に由来する構造単位の含有量は、アクリル系ゴム状重合体（ａ１）のスチレン類に由来する構造単位の含有量よりも多いことが好ましい。具体的には、ゴム粒子ｂのスチレン類に由来する構造単位の含有量は、アクリル系ゴム状重合体（ｂ１）を構成する全構造単位に対して５～６０質量％であることが好ましく、４０～６０質量％であることがより好ましい。スチレン類に由来する構造単位の含有量が多いほど、ゴム粒子ｂの硬度は、通常、高くなる。スチレン類に由来する構造単位の含有量が上記範囲内であると、ゴム粒子ｂを適度に硬くしうるため、引張弾性率を上記範囲内に調整しやすい。 However, when the acrylic rubber-like polymer (b1) constituting the rubber particles b contains structural units derived from styrenes, the content of the structural units derived from styrenes of the rubber particles b contained in the protective film B is , It is preferable that the content of the rubber particles a contained in the protective film A is larger than the content of the structural unit derived from styrenes. That is, the content of the structural unit derived from the styrenes of the acrylic rubber-like polymer (b1) is preferably higher than the content of the structural unit derived from the styrenes of the acrylic rubber-like polymer (a1). .. Specifically, the content of the structural units derived from the styrenes of the rubber particles b is preferably 5 to 60% by mass with respect to all the structural units constituting the acrylic rubber-like polymer (b1). More preferably, it is 40 to 60% by mass. The higher the content of structural units derived from styrenes, the higher the hardness of the rubber particles b. When the content of the structural unit derived from styrenes is within the above range, the rubber particles b can be appropriately hardened, so that the tensile elastic modulus can be easily adjusted within the above range.
　ゴム粒子ｂのガラス転移温度は、前述と同様に、室温以下（２５℃以下）でありうる。また、ゴム粒子ｂのガラス転移温度は、ゴム粒子ａのガラス転移温度よりも高いことが好ましい。 The glass transition temperature of the rubber particles b can be room temperature or lower (25 ° C. or lower) as described above. Further, the glass transition temperature of the rubber particles b is preferably higher than the glass transition temperature of the rubber particles a.
　保護フィルムＢにおけるゴム粒子ｂの含有量は、特に限定されないが、保護フィルムＢの引張弾性率を保護フィルムＡよりも高くする観点などから、保護フィルムＡにおけるゴム粒子ａの含有量よりも少ないことが好ましい。具体的には、保護フィルムＢにおけるゴム粒子ｂの含有量は、保護フィルムＢに対して２～１５質量％であることが好ましく、５～１２質量％であることがより好ましい。 The content of the rubber particles b in the protective film B is not particularly limited, but is smaller than the content of the rubber particles a in the protective film A from the viewpoint of making the tensile elastic modulus of the protective film B higher than that of the protective film A. Is preferable. Specifically, the content of the rubber particles b in the protective film B is preferably 2 to 15% by mass, and more preferably 5 to 12% by mass with respect to the protective film B.
　１－３－３．他の成分
　保護フィルムＢは、必要に応じて上記以外の他の成分をさらに含んでもよい。他の成分は、保護フィルムＡにおける他の成分と同様のものを使用できる。 1-3-3. Other components The protective film B may further contain components other than the above, if necessary. As the other component, the same component as the other component in the protective film A can be used.
　１－３－４．物性
　（引張弾性率）
　保護フィルムＢの引張弾性率は、特に限定されないが、偏光板を打ち抜く際のクラックや層間剥離を抑制しやすくする観点では、保護フィルムＡの引張弾性率よりも高いことが好ましい。偏光板の打ち抜き工程において、刃の押し込みによって保護フィルムＢに生じる応力は、保護フィルムＡに生じる応力よりも大きく、保護フィルムＢにおいてゴム粒子ｂにかかる負荷を調整する必要性が高いためである。すなわち、ゴム粒子ｂの周囲が柔らかい樹脂であると、刃から受けた力が樹脂に分散されやすくなるのに対し；ゴム粒子ｂの周囲が硬い樹脂であると、刃から受けた力が樹脂に発散されすぎず、ゴム粒子ｂが力を受けやすくなる。つまり、保護フィルムＢの引張弾性率を適度に高くすることで、ゴム粒子ｂに適度な負荷をかけやすくしうるため、偏光板の打抜き時にかかる応力をゴム粒子ｂで吸収しやすくなり、樹脂にクラックが入るのを抑制しやすくしうる。それにより、偏光板を打ち抜く際のクラックや層間剥離を抑制しやすくすることができる。保護フィルムＢと保護フィルムＡの２５℃における引張弾性率の差は、例えば０．３ＧＰａ以上としうる。保護フィルムＢの２５℃における引張弾性率は、２．４～３．４ＧＰａであることが好ましい。保護フィルムＢの引張弾性率は、前述と同様の方法で測定することができる。 1-3-4. Physical properties (tensile modulus)
The tensile elastic modulus of the protective film B is not particularly limited, but is preferably higher than the tensile elastic modulus of the protective film A from the viewpoint of facilitating suppression of cracks and delamination when punching the polarizing plate. This is because the stress generated in the protective film B by pushing the blade in the punching step of the polarizing plate is larger than the stress generated in the protective film A, and it is highly necessary to adjust the load applied to the rubber particles b in the protective film B. That is, if the circumference of the rubber particles b is a soft resin, the force received from the blade is easily dispersed in the resin; whereas if the circumference of the rubber particles b is a hard resin, the force received from the blade is distributed to the resin. The rubber particles b are more susceptible to force without being diverged too much. That is, by appropriately increasing the tensile elastic modulus of the protective film B, it is possible to easily apply an appropriate load to the rubber particles b, so that the stress applied when punching the polarizing plate is easily absorbed by the rubber particles b, and the resin It can make it easier to prevent cracks from forming. As a result, it is possible to easily suppress cracks and delamination when punching the polarizing plate. The difference in tensile elastic modulus between the protective film B and the protective film A at 25 ° C. can be, for example, 0.3 GPa or more. The tensile elastic modulus of the protective film B at 25 ° C. is preferably 2.4 to 3.4 GPa. The tensile elastic modulus of the protective film B can be measured by the same method as described above.
　保護フィルムＢの引張弾性率は、（メタ）アクリル系樹脂の組成やゴム粒子ｂの含有量および組成などによって調整されうる。保護フィルムＢの引張弾性率を高くする観点では、（メタ）アクリル系樹脂における、フェニルマレイミドに由来する構造単位（Ｕ２）／（フェニルマレイミドに由来する構造単位（Ｕ２）とアクリル酸アルキルエステルに由来する構造単位（Ｕ３）の合計）の比率を高くしたり、ゴム粒子ｂの含有量を少なくしたり、ゴム粒子ｂのスチレン類に由来する構造単位の含有量を多くしたりすることが好ましい。 The tensile elastic modulus of the protective film B can be adjusted by the composition of the (meth) acrylic resin, the content and composition of the rubber particles b, and the like. From the viewpoint of increasing the tensile elastic modulus of the protective film B, it is derived from the structural unit (U2) derived from phenylmaleimide / (structural unit (U2) derived from phenylmaleimide) and the acrylic acid alkyl ester in the (meth) acrylic resin. It is preferable to increase the ratio of the structural units (U3) to be formed), decrease the content of the rubber particles b, or increase the content of the structural units derived from styrenes of the rubber particles b.
　（ヘイズ）
　保護フィルムＢのヘイズは、前述と同様に、２．０％以下であることが好ましく、１．０％以下であることがより好ましい。 (Haze)
The haze of the protective film B is preferably 2.0% or less, and more preferably 1.0% or less, as described above.
　（位相差ＲｏおよびＲｔ）
　保護フィルムＢは、例えばＩＰＳモード用の位相差フィルムとして用いる観点では、測定波長５５０ｎｍ、２３℃５５％ＲＨの環境下で測定される面内方向の位相差Ｒｏは、０～１０ｎｍであることが好ましく、０～５ｎｍであることがより好ましい。保護フィルムＢの厚み方向の位相差Ｒｔは、－２０～２０ｎｍであることが好ましく、－１０～１０ｎｍであることがより好ましい。 (Phase difference Ro and Rt)
From the viewpoint of using the protective film B as a retardation film for IPS mode, for example, the in-plane retardation Ro measured in an environment with a measurement wavelength of 550 nm and 23 ° C. and 55% RH is 0 to 10 nm. It is preferably 0 to 5 nm, and more preferably 0 to 5 nm. The phase difference Rt in the thickness direction of the protective film B is preferably −20 to 20 nm, and more preferably −10 to 10 nm.
　ＲｏおよびＲｔは、それぞれ下記式で定義される。
　式（２ａ）：Ｒｏ＝（ｎｘ－ｎｙ）×ｄ
　式（２ｂ）：Ｒｔ＝（（ｎｘ＋ｎｙ）／２－ｎｚ）×ｄ
　（式中、
　ｎｘは、フィルムの面内遅相軸方向（屈折率が最大となる方向）の屈折率を表し、
　ｎｙは、フィルムの面内遅相軸に直交する方向の屈折率を表し、
　ｎｚは、フィルムの厚み方向の屈折率を表し、
　ｄは、フィルムの厚み（ｎｍ）を表す。） Ro and Rt are defined by the following equations, respectively.
Equation (2a): Ro = (nx-ny) × d
Equation (2b): Rt = ((nx + ny) /2-nz) × d
(During the ceremony,
nx represents the refractive index in the in-plane slow-phase axial direction (the direction in which the refractive index is maximized) of the film.
ny represents the refractive index in the direction orthogonal to the in-plane slow phase axis of the film.
nz represents the refractive index in the thickness direction of the film.
d represents the thickness (nm) of the film. )
　保護フィルムＢの面内遅相軸は、自動複屈折率計アクソスキャン（Ａｘｏ Ｓｃａｎ Ｍｕｅｌｌｅｒ Ｍａｔｒｉｘ Ｐｏｌａｒｉｍｅｔｅｒ：アクソメトリックス社製）により確認することができる。 The in-plane slow-phase axis of the protective film B can be confirmed by an automatic birefringence meter Axoscan (AxoScan Mueller Matrix Polarimeter: manufactured by Axometrics).
　ＲｏおよびＲｔは、以下の方法で測定することができる。
　１）保護フィルムを２３℃５５％ＲＨの環境下で２４時間調湿する。このフィルムの平均屈折率をアッベ屈折計で測定し、厚みｄを市販のマイクロメーターを用いて測定する。
　２）調湿後のフィルムの、測定波長５５０ｎｍにおけるリターデーションＲｏおよびＲｔを、それぞれ自動複屈折率計アクソスキャン（Ａｘｏ Ｓｃａｎ Ｍｕｅｌｌｅｒ Ｍａｔｒｉｘ Ｐｏｌａｒｉｍｅｔｅｒ：アクソメトリックス社製）を用いて、２３℃５５％ＲＨの環境下で測定する。 Ro and Rt can be measured by the following methods.
1) The protective film is humidity-controlled for 24 hours in an environment of 23 ° C. and 55% RH. The average refractive index of this film is measured with an Abbe refractometer, and the thickness d is measured with a commercially available micrometer.
2) The retardation Ro and Rt of the film after humidity control at a measurement wavelength of 550 nm were measured at 23 ° C. and 55% RH using an automatic birefringence meter Axoscan (Axo Scan Mueller Matrix Matrix Polarimeter), respectively. Measure in the environment.
　保護フィルムＢの位相差ＲｏおよびＲｔは、例えば（メタ）アクリル系樹脂のモノマー組成や延伸条件によって調整することができる。保護フィルムＢの位相差ＲｏおよびＲｔを低くするためには、延伸によって位相差が出にくい（メタ）アクリル系樹脂を用いる（例えば負の複屈折を有するモノマー由来の構造単位と、正の複屈折を有するモノマー由来の構造単位とで位相差を相殺できるようなモノマー比率にする）ことが好ましい。 The phase difference Ro and Rt of the protective film B can be adjusted by, for example, the monomer composition of the (meth) acrylic resin and the stretching conditions. In order to reduce the phase difference Ro and Rt of the protective film B, a (meth) acrylic resin that does not easily generate a phase difference due to stretching is used (for example, a structural unit derived from a monomer having negative birefringence and a positive birefringence. It is preferable to set the monomer ratio so that the phase difference can be offset with the structural unit derived from the monomer having.
　（残留溶媒量）
　保護フィルムＢは、好ましくはキャスト法で製膜されることから、残留溶媒をさらに含みうる。残留溶媒量は、保護フィルムＢに対して７００ｐｐｍ以下であることが好ましく、３０～７００ｐｐｍであることがより好ましい。残留溶媒の含有量は、保護フィルムの製造工程における、支持体上に流延させたドープの乾燥条件によって調整されうる。 (Amount of residual solvent)
Since the protective film B is preferably formed by a casting method, it may further contain a residual solvent. The amount of residual solvent is preferably 700 ppm or less, more preferably 30 to 700 ppm, based on the protective film B. The content of the residual solvent can be adjusted by the drying conditions of the dope cast on the support in the process of manufacturing the protective film.
　保護フィルムＢの残留溶媒量は、ヘッドスペースガスクロマトグラフィーにより測定することができる。ヘッドスペースガスクロマトグラフィー法では、試料を容器に封入し、加熱し、容器中に揮発成分が充満した状態で速やかに容器中のガスをガスクロマトグラフに注入し、質量分析を行って化合物の同定を行いながら揮発成分を定量するものである。ヘッドスペース法では、ガスクロマトグラフにより、揮発成分の全ピークを観測することを可能にするとともに、電磁気的相互作用を利用した分析法を用いることによって、高精度で揮発性物質やモノマーなどの定量も併せて行うことができる。 The amount of residual solvent in the protective film B can be measured by headspace gas chromatography. In the headspace gas chromatography method, a sample is sealed in a container, heated, and the gas in the container is promptly injected into a gas chromatograph with the container filled with volatile components, and mass spectrometry is performed to identify the compound. The volatile components are quantified while doing so. In the headspace method, it is possible to observe all peaks of volatile components by gas chromatography, and by using an analytical method that utilizes electromagnetic interaction, it is possible to quantify volatile substances and monomers with high accuracy. It can be done at the same time.
　（厚み）
　保護フィルムＢの厚みは、特に制限されないが、保護フィルムＡの厚みよりも薄いことが好ましい。保護フィルムＢの厚みが相対的に薄いと、偏光板の打ち抜き工程において、刃を抜く際に、刃が引っかかりにくくしうるだけでなく、刃を押し込んだときの物理的な変形も少なくしうる。それにより、偏光板を打ち抜く際のクラックを一層抑制しうる。例えば、保護フィルムＢの厚みは、保護フィルムＡの厚みに対して２０～７７％としうる。具体的には、保護フィルムＢの厚みは、１０～６０μｍであることが好ましく、１０～４０μｍであることがより好ましい。 (Thickness)
The thickness of the protective film B is not particularly limited, but is preferably thinner than the thickness of the protective film A. When the thickness of the protective film B is relatively thin, not only can the blade be less likely to be caught when the blade is punched in the punching step of the polarizing plate, but also physical deformation when the blade is pushed in can be reduced. As a result, cracks when punching the polarizing plate can be further suppressed. For example, the thickness of the protective film B can be 20 to 77% of the thickness of the protective film A. Specifically, the thickness of the protective film B is preferably 10 to 60 μm, more preferably 10 to 40 μm.
　１－３－５．保護フィルムＡおよびＢの製造方法
　保護フィルムＡおよびＢは、任意の方法で製造されてよく、溶液流延方式（キャスト法）で製造されてもよいし、溶融流延方式（メルト）で製造されてもよい。 1-3-5. Methods for Producing Protective Films A and B Protective films A and B may be manufactured by any method, may be manufactured by a solution casting method (cast method), or may be manufactured by a melt casting method (melt). You may.
　保護フィルムＡは、例えば溶融流延方式（メルト）で製造されうる。溶融流延方式（メルト）では、（メタ）アクリル系樹脂と、ゴム粒子とを含む樹脂組成物を溶融押出する工程、押し出された樹脂組成物を冷却固化する工程、および、必要に応じて冷却固化して得られる膜状物を延伸する工程を経て保護フィルムを得ることができる。保護フィルムＡを製造する際の延伸倍率は、特に制限されないが、ゴム粒子ａの平均アスペクト比をゴム粒子ｂよりも小さくする観点では、保護フィルムＢの製造時の延伸倍率よりも低いこと、例えば１０％以下であることが好ましく、未延伸であることがより好ましい。 The protective film A can be manufactured by, for example, a melt casting method (melt). In the melt casting method (melt), a step of melt-extruding a resin composition containing a (meth) acrylic resin and rubber particles, a step of cooling and solidifying the extruded resin composition, and cooling as necessary. A protective film can be obtained through a step of stretching a film-like substance obtained by solidification. The draw ratio when the protective film A is manufactured is not particularly limited, but is lower than the draw ratio when the protective film B is manufactured, for example, from the viewpoint of making the average aspect ratio of the rubber particles a smaller than that of the rubber particles b. It is preferably 10% or less, and more preferably unstretched.
　保護フィルムＢは、使用できる材料の制限を少なくしうる観点から、キャスト法で製造されることが好ましい。すなわち、保護フィルムＡは、少なくとも、１）前述の（メタ）アクリル系樹脂と、ゴム粒子と、溶媒とを含むドープを得る工程と、２）得られたドープを支持体上に流延した後、乾燥および剥離して、膜状物を得る工程と、３）得られた膜状物を、必要に応じて延伸しながら乾燥させる工程とを経て製造されうる。 The protective film B is preferably manufactured by the casting method from the viewpoint of reducing the restrictions on the materials that can be used. That is, the protective film A has at least 1) a step of obtaining a dope containing the above-mentioned (meth) acrylic resin, rubber particles, and a solvent, and 2) after casting the obtained dope onto a support. It can be produced through a step of obtaining a film-like substance by drying and peeling, and a step of 3) drying the obtained film-like substance while stretching it if necessary.
　１）の工程について
　（メタ）アクリル系樹脂とゴム粒子ａまたはｂ（以下、まとめて「ゴム粒子」ともいう）とを、溶媒に溶解または分散させて、ドープを調製する。 Regarding step 1), a (meth) acrylic resin and rubber particles a or b (hereinafter collectively referred to as “rubber particles”) are dissolved or dispersed in a solvent to prepare a dope.
　ドープに用いられる溶媒は、少なくとも（メタ）アクリル系樹脂を溶解させうる有機溶媒（良溶媒）を含む。良溶媒の例には、メチレンクロライドなどの塩素系有機溶媒や；酢酸メチル、酢酸エチル、アセトン、テトラヒドロフランなどの非塩素系有機溶媒が含まれる。中でも、メチレンクロライドが好ましい。 The solvent used for doping includes at least an organic solvent (good solvent) capable of dissolving the (meth) acrylic resin. Examples of good solvents include chlorine-based organic solvents such as methylene chloride; non-chlorine-based organic solvents such as methyl acetate, ethyl acetate, acetone and tetrahydrofuran. Of these, methylene chloride is preferable.
　ドープに用いられる溶媒は、貧溶媒をさらに含んでいてもよい。貧溶媒の例には、炭素原子数１～４の直鎖または分岐鎖状の脂肪族アルコールが含まれる。ドープ中のアルコールの比率が高くなると、膜状物がゲル化しやすく、金属支持体からの剥離が容易になりやすい。炭素原子数１～４の直鎖または分岐鎖状の脂肪族アルコールとしては、メタノール、エタノール、ｎ－プロパノール、ｉｓｏ－プロパノール、ｎ－ブタノール、ｓｅｃ－ブタノール、ｔｅｒｔ－ブタノールを挙げることができる。これらのうちドープの安定性、沸点も比較的低く、乾燥性もよいことなどからエタノールが好ましい。 The solvent used for doping may further contain a poor solvent. Examples of poor solvents include straight-chain or branched-chain aliphatic alcohols having 1 to 4 carbon atoms. When the ratio of alcohol in the doping is high, the film-like substance tends to gel and peels off from the metal support easily. Examples of the linear or branched aliphatic alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, and tert-butanol. Of these, ethanol is preferable because of its stability of doping, relatively low boiling point, and good drying property.
　２）の工程について
　得られたドープを、支持体上に流延する。ドープの流延は、流延ダイから吐出させて行うことができる。 The dope obtained in step 2) is cast on the support. Doping can be cast by discharging from a casting die.
　次いで、支持体上に流延されたドープ中の溶媒を蒸発させ、乾燥させる。乾燥されたドープを支持体から剥離して、膜状物を得る。 Next, the solvent in the dope cast on the support is evaporated and dried. The dried dope is stripped from the support to give a film.
　支持体から剥離する際のドープの残留溶媒量（剥離時の膜状物の残留溶媒量）は、例えば２５質量％以上であることが好ましく、３０～３７質量％であることがより好ましい。剥離時の残留溶媒量が３７質量％以下であると、剥離による膜状物が伸びすぎるのを抑制しやすい。 The residual solvent amount of the doping when peeling from the support (the residual solvent amount of the film-like substance at the time of peeling) is preferably, for example, 25% by mass or more, and more preferably 30 to 37% by mass. When the amount of residual solvent at the time of peeling is 37% by mass or less, it is easy to prevent the film-like material from being excessively stretched due to peeling.
　剥離時のドープの残留溶媒量は、下記式で定義される。以下においても同様である。
　ドープの残留溶媒量（質量％）＝（ドープの加熱処理前質量－ドープの加熱処理後質量）／ドープの加熱処理後質量×１００
　尚、残留溶媒量を測定する際の加熱処理とは、１４０℃３０分の加熱処理をいう。 The residual solvent amount of the doping at the time of peeling is defined by the following formula. The same applies to the following.
Residual solvent amount of doping (mass%) = (mass before heat treatment of doping-mass after heat treatment of doping) / mass after heat treatment of doping × 100
The heat treatment for measuring the amount of residual solvent means a heat treatment at 140 ° C. for 30 minutes.
　剥離時の残留溶媒量は、支持体上でのドープの乾燥温度や乾燥時間、支持体の温度などによって調整することができる。 The amount of residual solvent at the time of peeling can be adjusted by adjusting the drying temperature and drying time of the doping on the support, the temperature of the support, and the like.
　３）の工程について
　得られた膜状物を乾燥させる。乾燥は、一段階で行ってもよいし、多段階で行ってもよい。また、乾燥は、必要に応じて延伸しながら行ってもよい。 About the step 3) The obtained film-like material is dried. Drying may be performed in one step or in multiple steps. Further, drying may be carried out while stretching, if necessary.
　例えば、膜状物の乾燥工程は、膜状物を予備乾燥させる工程（予備乾燥工程）と、膜状物を延伸する工程（延伸工程）と、延伸後の膜状物を乾燥させる工程（本乾燥工程）とを含んでもよい。 For example, the drying step of the film-like material includes a step of pre-drying the film-like material (pre-drying step), a step of stretching the film-like material (stretching step), and a step of drying the stretched film-like material (main Drying step) and may be included.
　（予備乾燥工程）
　予備乾燥温度（延伸前の乾燥温度）は、延伸温度よりも高い温度でありうる。具体的には、（メタ）アクリル系樹脂のガラス転移温度をＴｇとしたとき、Ｔｇ（℃）以上であることが好ましく、（Ｔｇ＋１０）～（Ｔｇ＋５０）℃であることがより好ましい。予備乾燥温度がＴｇ（℃）以上、好ましくは（Ｔｇ＋１０）℃以上であると、溶媒を適度に揮発させやすいため、搬送性（ハンドリング性）を高めやすく、（Ｔｇ＋５０）℃以下であると、溶媒が揮発しすぎないため、この後の延伸工程における延伸性が損なわれにくい。初期乾燥温度は、（ａ）テンター延伸機やローラーで搬送しながら非接触加熱型で乾燥させる場合は、延伸機内温度または熱風温度などの雰囲気温度として測定されうる。 (Preliminary drying process)
The pre-drying temperature (drying temperature before stretching) can be higher than the stretching temperature. Specifically, when the glass transition temperature of the (meth) acrylic resin is Tg, it is preferably Tg (° C.) or higher, and more preferably (Tg + 10) to (Tg + 50) ° C. When the pre-drying temperature is Tg (° C.) or higher, preferably (Tg + 10) ° C. or higher, the solvent is likely to be volatilized appropriately, so that the transportability (handleability) is easily improved. Is not excessively volatilized, so that the stretchability in the subsequent stretching step is not easily impaired. The initial drying temperature can be measured as (a) an atmospheric temperature such as the temperature inside the stretching machine or the hot air temperature when the drying is performed by the non-contact heating type while being conveyed by a tenter stretching machine or a roller.
　（延伸工程）
　延伸は、求められる光学特性に応じて行えばよく、少なくとも一方の方向に延伸することが好ましく、互いに直交する二方向に延伸（例えば、膜状物の幅方向（ＴＤ方向）と、それと直交する搬送方向（ＭＤ方向）の二軸延伸）してもよい。 (Stretching process)
Stretching may be performed according to the required optical characteristics, and is preferably stretched in at least one direction, and stretches in two directions orthogonal to each other (for example, the width direction (TD direction) of the film-like object and orthogonal to it. Biaxial stretching in the transport direction (MD direction)) may be performed.
　保護フィルムＢに含まれるゴム粒子ｂの平均アスペクト比を上記範囲に調整しやすくする観点では、保護フィルムＢを製造する際の延伸倍率は、保護フィルムＡの製造時の延伸倍率よりも高いことが好ましい。具体的には、保護フィルムＢを製造する際の延伸倍率は、４０～１００％であることが好ましく、６０～１００％であることがより好ましい。二軸延伸する場合は、各方向にける延伸倍率が、それぞれ上記範囲内であることが好ましい。 From the viewpoint of facilitating the adjustment of the average aspect ratio of the rubber particles b contained in the protective film B within the above range, the draw ratio when the protective film B is manufactured may be higher than the stretch ratio when the protective film A is manufactured. preferable. Specifically, the draw ratio when producing the protective film B is preferably 40 to 100%, more preferably 60 to 100%. In the case of biaxial stretching, it is preferable that the stretching ratio in each direction is within the above range.
　延伸倍率（％）は、（延伸後のフィルムの延伸方向大きさ－延伸前のフィルムの延伸方向大きさ）／（延伸前のフィルムの延伸方向大きさ）×１００として定義される。なお、二軸延伸を行う場合は、ＴＤ方向とＭＤ方向のそれぞれについて、上記延伸倍率とすることが好ましい。 The stretch ratio (%) is defined as (size of the film after stretching in the stretching direction-size of the film before stretching in the stretching direction) / (size of the film before stretching in the stretching direction) × 100. When biaxial stretching is performed, it is preferable to set the stretching ratio in each of the TD direction and the MD direction.
　延伸温度（延伸時の乾燥温度）は、前述と同様に、（メタ）アクリル系樹脂のガラス転移温度をＴｇとしたとき、Ｔｇ（℃）以上であることが好ましく、（Ｔｇ＋１０）～（Ｔｇ＋５０）℃であることがより好ましい。延伸温度がＴｇ（℃）以上、好ましくは（Ｔｇ＋１０）℃以上であると、溶媒を適度に揮発させやすいため、延伸張力を適切な範囲に調整しやすく、（Ｔｇ＋５０）℃以下であると、溶媒が揮発しすぎないため、延伸性が損なわれにくい。保護フィルムＢの製造時における延伸温度は、例えば１１５℃以上としうる。延伸温度は、前述と同様に、（ａ）延伸機内温度などの雰囲気温度を測定することが好ましい。 The stretching temperature (drying temperature during stretching) is preferably Tg (° C.) or higher, and is preferably (Tg + 10) to (Tg + 50), when the glass transition temperature of the (meth) acrylic resin is Tg, as described above. More preferably, it is ° C. When the stretching temperature is Tg (° C.) or higher, preferably (Tg + 10) ° C. or higher, the solvent is likely to volatilize appropriately, so that the stretching tension can be easily adjusted to an appropriate range, and when it is (Tg + 50) ° C. or lower, the solvent Does not volatilize too much, so stretchability is not easily impaired. The stretching temperature during production of the protective film B can be, for example, 115 ° C. or higher. As for the stretching temperature, it is preferable to measure the ambient temperature such as (a) the temperature inside the stretching machine, as described above.
　延伸開始時の膜状物中の残留溶媒量は、剥離時の膜状物中の残留溶媒量と同程度であることが好ましく、例えば２０～３０質量％であることが好ましく、２５～３０質量％であることがより好ましい。 The amount of residual solvent in the film-like material at the start of stretching is preferably about the same as the amount of residual solvent in the film-like material at the time of peeling, for example, preferably 20 to 30% by mass, and 25 to 30% by mass. More preferably.
　膜状物のＴＤ方向（幅方向）の延伸は、例えば膜状物の両端をクリップやピンで固定し、クリップやピンの間隔を進行方向に広げる方法（テンター法）で行うことができる。膜状物のＭＤ方向の延伸は、例えば複数のロールに周速差をつけ、その間でロール周速差を利用する方法（ロール法）で行うことができる。 Stretching of the film-like object in the TD direction (width direction) can be performed by, for example, fixing both ends of the film-like object with clips or pins and widening the distance between the clips or pins in the traveling direction (tenter method). Stretching of the film-like material in the MD direction can be performed by, for example, a method (roll method) in which a plurality of rolls are provided with a peripheral speed difference and the roll peripheral speed difference is used between them.
　（本乾燥工程）
　残留溶媒量をより低減させる観点から、延伸後に得られた膜状物をさらに乾燥させることが好ましい。例えば、延伸後に得られた膜状物を、ロールなどで搬送しながらさらに乾燥させることが好ましい。 (Main drying process)
From the viewpoint of further reducing the amount of residual solvent, it is preferable to further dry the film-like product obtained after stretching. For example, it is preferable to further dry the film-like substance obtained after stretching while transporting it with a roll or the like.
　本乾燥温度（未延伸の場合は乾燥温度）は、（メタ）アクリル系樹脂のガラス転移温度をＴｇとしたとき、（Ｔｇ－５０）～（Ｔｇ－３０）℃であることが好ましく、（Ｔｇ－４０）～（Ｔｇ－３０）℃であることがより好ましい。後乾燥温度が（Ｔｇ－５０）℃以上であると、延伸後の膜状物から溶媒を十分に揮発除去しやすく、（Ｔｇ－３０）℃以下であると、膜状物の変形などを高度に抑制しうる。本乾燥温度は、前述と同様に、（ａ）熱風温度などの雰囲気温度を測定することが好ましい。 The main drying temperature (drying temperature in the case of unstretched) is preferably (Tg-50) to (Tg-30) ° C., where Tg is the glass transition temperature of the (meth) acrylic resin, and (Tg). More preferably, it is −40) to (Tg-30) ° C. When the post-drying temperature is (Tg-50) ° C. or higher, it is easy to sufficiently volatilize and remove the solvent from the film-like material after stretching, and when it is (Tg-30) ° C. or lower, the film-like material is highly deformed. Can be suppressed. As the main drying temperature, it is preferable to measure the ambient temperature such as (a) hot air temperature as described above.
　１－４．接着剤層ＡおよびＢ
　接着剤層Ａは、保護フィルムＡと偏光子との間に配置され、それらを接着させる。同様に、接着剤層Ｂは、保護フィルムＢと偏光子との間に配置され、それらを接着させる。 1-4. Adhesive layers A and B
The adhesive layer A is arranged between the protective film A and the polarizer and adheres them. Similarly, the adhesive layer B is placed between the protective film B and the polarizer and adheres them.
　接着剤層ＡおよびＢは、完全ケン化型ポリビニルアルコール水溶液（水糊）から得られる層であってもよいし、活性エネルギー線硬化性接着剤の硬化物層であってもよい。（メタ）アクリル系樹脂を含む保護フィルムＡおよびＢとの親和性が高く、良好に接着させやすい観点では、接着剤層ＡおよびＢは、活性エネルギー線硬化性接着剤の硬化物層であることが好ましい。 The adhesive layers A and B may be layers obtained from a completely saponified polyvinyl alcohol aqueous solution (water glue), or may be a cured product layer of an active energy ray-curable adhesive. From the viewpoint of having high affinity with the protective films A and B containing the (meth) acrylic resin and facilitating good adhesion, the adhesive layers A and B are cured product layers of the active energy ray-curable adhesive. Is preferable.
　活性エネルギー線硬化性接着剤は、光ラジカル重合性組成物であってもよいし、光カチオン重合性組成物であってもよい。中でも、光カチオン重合性組成物が好ましい。 The active energy ray-curable adhesive may be a photoradical polymerizable composition or a photocationic polymerizable composition. Of these, a photocationically polymerizable composition is preferable.
　光カチオン重合性組成物は、エポキシ系化合物と、光カチオン重合開始剤とを含む。 The photocationic polymerizable composition contains an epoxy compound and a photocationic polymerization initiator.
　エポキシ系化合物とは、分子内に１以上、好ましくは２以上のエポキシ基を有する化合物である。エポキシ系化合物の例には、脂環式ポリオールに、エピクロロヒドリンを反応させて得られる水素化エポキシ系化合物（脂環式環を有するポリオールのグリシジルエーテル）；脂肪族多価アルコールまたはそのアルキレンオキサイド付加物のポリグリシジルエーテルなどの脂肪族エポキシ系化合物；脂環式環に結合したエポキシ基を分子内に１以上有する脂環式エポキシ系化合物が含まれる。エポキシ系化合物は、１種のみを使用してもよいし、２種以上を併用してもよい。 The epoxy compound is a compound having one or more, preferably two or more epoxy groups in the molecule. Examples of epoxy compounds include hydrogenated epoxy compounds obtained by reacting an alicyclic polyol with epichlorohydrin (glycidyl ether of a polyol having an alicyclic ring); an aliphatic polyhydric alcohol or an alkylene thereof. Aliphatic epoxy compounds such as polyglycidyl ether as an oxide adduct; include alicyclic epoxy compounds having one or more alicyclic ring-bonded epoxy groups in the molecule. Only one type of epoxy compound may be used, or two or more types may be used in combination.
　光カチオン重合開始剤は、例えば芳香族ジアゾニウム塩；芳香族ヨードニウム塩や芳香族スルホニウム塩などのオニウム塩；鉄－アレーン錯体などでありうる。 The photocationic polymerization initiator may be, for example, an aromatic diazonium salt; an onium salt such as an aromatic iodonium salt or an aromatic sulfonium salt; an iron-alene complex or the like.
　光カチオン重合開始剤は、必要に応じてオキセタン、ポリオールなどのカチオン重合促進剤、光増感剤、イオントラップ剤、酸化防止剤、連鎖移動剤、粘着付与剤、熱可塑性樹脂、充填剤、流動調整剤、可塑剤、消泡剤、帯電防止剤、レベリング剤、溶剤などの添加剤をさらに含んでもよい。 The photocationic polymerization initiator may be a cationic polymerization accelerator such as oxetane or polyol, a photosensitizer, an ion trapping agent, an antioxidant, a chain transfer agent, a tackifier, a thermoplastic resin, a filler, or a fluidized agent, if necessary. Additives such as modifiers, plasticizers, defoamers, antistatic agents, leveling agents, solvents and the like may be further included.
　接着剤層ＡおよびＢの厚みは、特に限定されないが、例えば０．０１～１０μｍであり、好ましくは０．０１～５μｍ程度でありうる。 The thicknesses of the adhesive layers A and B are not particularly limited, but may be, for example, 0.01 to 10 μm, preferably about 0.01 to 5 μm.
　１－５．粘着剤層
　粘着剤層は、偏光板の保護フィルムＢの、偏光子とは反対側の面に配置されている。本発明の偏光板は、当該粘着剤層を介して液晶セルなどの表示素子と貼り合わされる。 1-5. Adhesive layer The adhesive layer is arranged on the surface of the protective film B of the polarizing plate on the side opposite to the polarizer. The polarizing plate of the present invention is bonded to a display element such as a liquid crystal cell via the pressure-sensitive adhesive layer.
　粘着剤層を構成する粘着剤は、特に制限されず、例えば、アクリル系粘着剤、シリコーン系粘着剤、ゴム系粘着剤などでありうる。透明性、耐候性、耐熱性、加工性の観点では、アクリル系粘着剤が好ましい。 The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is not particularly limited, and may be, for example, an acrylic pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, or the like. Acrylic adhesives are preferable from the viewpoints of transparency, weather resistance, heat resistance, and processability.
　粘着剤は、必要に応じて粘着付与剤、可塑剤、ガラス繊維、ガラスビーズ、金属粉、その他の充填剤、顔料、着色剤、充填剤、酸化防止剤、紫外線吸収剤、シランカップリング剤など、各種の添加剤をさらに含んでもよい。 Adhesives include tackifiers, plasticizers, glass fibers, glass beads, metal powders, other fillers, pigments, colorants, fillers, antioxidants, UV absorbers, silane coupling agents, etc., as required. , Various additives may be further included.
　粘着剤層の厚みは、通常、３～１００μｍ程度であり、好ましくは５～５０μｍである。 The thickness of the pressure-sensitive adhesive layer is usually about 3 to 100 μm, preferably 5 to 50 μm.
　粘着剤層の表面は、離型処理が施された剥離フィルムで保護されている。剥離フィルムの例には、アクリルフィルム、ポリカーボネートフィルム、ポリエステルフィルム、フッ素樹脂フィルムなどのプラスチックフィルムが含まれる。 The surface of the adhesive layer is protected by a release film that has undergone a mold release treatment. Examples of the release film include plastic films such as acrylic films, polycarbonate films, polyester films and fluororesin films.
　２．偏光板の製造方法
　本発明の偏光板は、１）偏光子の一方の面に、接着剤を介して保護フィルムＡを積層し、貼り合わせる工程と、２）偏光子の他方の面に、接着剤を介して保護フィルムＢを積層し、貼り合わせる工程と、３）貼り合わせた積層物の保護フィルムＢ上に、粘着剤層およびその保護フィルムを貼り付けて、偏光板を得る工程とを経て得られる。以下、接着剤として活性エネルギー線硬化性接着剤を用いる例で説明する。 2. Method for manufacturing a polarizing plate The polarizing plate of the present invention has a step of 1) laminating and bonding a protective film A on one surface of a polarizing element via an adhesive, and 2) bonding to the other surface of the polarizing element. Through a step of laminating and laminating the protective film B via an agent, and 3) a step of laminating the adhesive layer and the protective film on the bonded laminated protective film B to obtain a polarizing plate. can get. Hereinafter, an example in which an active energy ray-curable adhesive is used as the adhesive will be described.
　１）の工程について
　保護フィルムＡの表面に、必要に応じてコロナ処理などの表面処理を施す。次いで、偏光子の一方の面に、活性エネルギー線硬化性接着剤の層を介して、保護フィルムＡを（表面処理されている場合は、保護フィルムＡの表面処理面が偏光子側となるように）積層した後、活性エネルギー線を照射して、活性エネルギー線硬化性接着剤を硬化させる。それにより、偏光子と保護フィルムＡとを、活性エネルギー線硬化性接着剤の硬化物層を介して接着させて、貼り合わせる。 About step 1) The surface of the protective film A is subjected to surface treatment such as corona treatment as necessary. Next, a protective film A is applied to one surface of the polarizing element via a layer of an active energy ray-curable adhesive (in the case of surface treatment, the surface-treated surface of the protective film A is on the polarizer side). After laminating, the active energy ray-curable adhesive is cured by irradiating it with active energy rays. As a result, the polarizer and the protective film A are bonded to each other via the cured product layer of the active energy ray-curable adhesive.
　２）の工程について
　同様に、保護フィルムＢの表面に、必要に応じてコロナ処理などの表面処理を施す。次いで、偏光子の他方の面に、活性エネルギー線硬化性接着剤の層を介して、保護フィルムＢを（表面処理されている場合は、保護フィルムＢの表面処理面が偏光子側となるように）積層した後、活性エネルギー線を照射して、活性エネルギー線硬化性接着剤を硬化させる。それにより、偏光子と保護フィルムＢとを、活性エネルギー線硬化性接着剤の硬化物層を介して接着させて、貼り合わせる。 Similarly, regarding the step 2), the surface of the protective film B is subjected to a surface treatment such as a corona treatment, if necessary. Next, a protective film B is applied to the other surface of the polarizer via a layer of an active energy ray-curable adhesive (in the case of surface treatment, the surface-treated surface of the protective film B is on the polarizer side). After laminating, the active energy ray-curable adhesive is cured by irradiating it with active energy rays. As a result, the polarizer and the protective film B are bonded to each other via the cured product layer of the active energy ray-curable adhesive.
　１）の工程と２）の工程は、同時に行ってもよいし、逐次的に行ってもよい。製造効率を高める観点では、１）の工程と２）の工程とは同時に行うことが好ましい。 The steps 1) and 2) may be performed simultaneously or sequentially. From the viewpoint of increasing production efficiency, it is preferable that the steps 1) and 2) are performed at the same time.
　１）の工程と２）の工程とは同時に行う場合、保護フィルムＡ、偏光子、および保護フィルムＢの積層は、ロールツーロール方式で行うことが好ましい。そして、得られた積層物に活性エネルギー線を照射して、活性エネルギー線硬化性接着剤を硬化させればよい。 When the steps 1) and 2) are performed at the same time, it is preferable that the protective film A, the polarizer, and the protective film B are laminated by a roll-to-roll method. Then, the obtained laminate may be irradiated with active energy rays to cure the active energy ray-curable adhesive.
　３）の工程について
　次いで、得られた偏光板の保護フィルムＢ上に、粘着剤層およびその剥離フィルムを貼り付ける。具体的には、保護フィルムＢ上に、粘着剤層を設けた剥離フィルムを転写するなどの方法により、粘着剤層を形成することができる。 Regarding the step 3) Next, the pressure-sensitive adhesive layer and its release film are attached onto the protective film B of the obtained polarizing plate. Specifically, the pressure-sensitive adhesive layer can be formed by a method such as transferring a release film provided with the pressure-sensitive adhesive layer on the protective film B.
　得られる偏光板は、長尺状の偏光板でありうる。長尺状の偏光板は、ロール状に巻き取られて、偏光板のロール体とされる。そして、偏光板のロール体は、使用時（例えば、表示装置の製造時）に繰り出された後、任意の大きさおよび形状に打ち抜かれて、表示装置の製造に供される。偏光板の打ち抜きは、保護フィルムＡ側から刃の押し込むことによって行われる（図２Ａ参照）。 The obtained polarizing plate can be a long polarizing plate. The elongated polarizing plate is wound into a roll to form a rolled body of the polarizing plate. Then, the roll body of the polarizing plate is unwound at the time of use (for example, at the time of manufacturing the display device), and then punched into an arbitrary size and shape to be used for manufacturing the display device. The punching of the polarizing plate is performed by pushing the blade from the protective film A side (see FIG. 2A).
　３．表示装置
　本発明の表示装置は、本発明の偏光板を含む。本発明の表示装置は、液晶表示装置や有機ＥＬ表示装置などであり、好ましくは液晶表示装置でありうる。 3. 3. Display device The display device of the present invention includes the polarizing plate of the present invention. The display device of the present invention is a liquid crystal display device, an organic EL display device, or the like, and may be a liquid crystal display device.
　すなわち、本発明の液晶表示装置は、液晶セルと、液晶セルの一方の面に配置された第一偏光板と、液晶セルの他方の面に配置された第二偏光板とを含む。 That is, the liquid crystal display device of the present invention includes a liquid crystal cell, a first polarizing plate arranged on one surface of the liquid crystal cell, and a second polarizing plate arranged on the other surface of the liquid crystal cell.
　液晶セルの表示モードは、例えばＳＴＮ（Super-Twisted Nematic）、ＴＮ（Twisted Nematic）、ＯＣＢ（Optically Compensated Bend）、ＨＡＮ（Hybridaligned Nematic）、ＶＡ（Vertical Alignment、ＭＶＡ（Multi-domain Vertical Alignment）、ＰＶＡ（Patterned Vertical Alignment））、ＩＰＳ（In-Plane-Switching）などでありうる。例えば、携帯機器用途の液晶表示装置では、ＩＰＳモードが好ましい。 The display modes of the liquid crystal cells are, for example, STN (Super-Twisted Nematic), TN (Twisted Nematic), OCB (Optically Compensated Bend), HAN (Hybridaligned Nematic), VA (Vertical Alignment, MVA (Multi-domain Vertical Alignment), PVA). (Patterned Vertical Alignment)), IPS (In-Plane-Switching), etc. For example, in a liquid crystal display device for mobile devices, the IPS mode is preferable.
　第一偏光板および第二偏光板のうち一方または両方が、本発明の偏光板でありうる。本発明の偏光板は、粘着剤層が液晶セルと密着するように配置される。 One or both of the first polarizing plate and the second polarizing plate can be the polarizing plate of the present invention. The polarizing plate of the present invention is arranged so that the pressure-sensitive adhesive layer is in close contact with the liquid crystal cell.
　以下、実施例により本発明を具体的に説明するが、本発明はこれらに限定されるものではない。 Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited thereto.
　１．保護フィルムの材料
　（１）（メタ）アクリル系樹脂
　表１に示される（メタ）アクリル系樹脂１～９を準備した。
Figure JPOXMLDOC01-appb-T000001
 1. 1. Materials for Protective Film (1) (Meta) Acrylic Resins The (meth) acrylic resins 1 to 9 shown in Table 1 were prepared.
Figure JPOXMLDOC01-appb-T000001
　（メタ）アクリル系樹脂１～９のガラス転移温度および重量平均分子量は、以下の方法で測定した。 The glass transition temperature and weight average molecular weight of the (meth) acrylic resins 1 to 9 were measured by the following methods.
　（ガラス転移温度）
　（メタ）アクリル系樹脂のガラス転移温度（Ｔｇ）は、ＤＳＣ（Ｄｉｆｆｅｒｅｎｔｉａｌ Ｓｃａｎｎｉｎｇ Ｃｏｌｏｒｉｍｅｔｒｙ：示差走査熱量法）を用いて、ＪＩＳ Ｋ ７１２１－２０１２に準拠して測定した。 (Glass-transition temperature)
The glass transition temperature (Tg) of the (meth) acrylic resin was measured using DSC (Differential Scanning Colorimetry) according to JIS K 7121-2012.
　（重量平均分子量）
　（メタ）アクリル系樹脂の重量平均分子量（Ｍｗ）は、ゲル浸透クロマトグラフィー（東ソー社製 ＨＬＣ８２２０ＧＰＣ）、カラム（東ソー社製 ＴＳＫ－ＧＥＬ  Ｇ６０００ＨＸＬ－Ｇ５０００ＨＸＬ－Ｇ５０００ＨＸＬ－Ｇ４０００ＨＸＬ－Ｇ３０００ＨＸＬ  直列）を用いて測定した。試料２０ｍｇ±０．５ｍｇをテトラヒドロフラン１０ｍｌに溶解し、０．４５ｍｍのフィルターで濾過した。この溶液をカラム（温度４０℃）に１００ｍｌ注入し、検出器ＲＩ温度４０℃で測定し、スチレン換算した値を用いた。 (Weight average molecular weight)
The weight average molecular weight (Mw) of the (meth) acrylic resin was measured using gel permeation chromatography (HLC8220GPC manufactured by Tosoh Corporation) and a column (TSK-GEL G6000HXL-G5000HXL-G5000HXL-G4000HXL-G3000HXL series manufactured by Tosoh Corporation). .. 20 mg ± 0.5 mg of the sample was dissolved in 10 ml of tetrahydrofuran and filtered through a 0.45 mm filter. 100 ml of this solution was injected into a column (temperature 40 ° C.), measured at a detector RI temperature of 40 ° C., and a styrene-converted value was used.
　（２）ゴム粒子
　＜ゴム粒子Ｒ１の調製＞
　撹拌機付き８Ｌ重合装置に、以下の化合物を仕込んだ。
　脱イオン水：１７５質量部
　ポリオキシエチレンラウリルエーテルリン酸：０．１０４質量部
　ホウ酸：０．４７２５質量部
　炭酸ナトリウム：０．０４７２５質量部 (2) Rubber particles <Preparation of rubber particles R1>
The following compounds were charged into an 8 L polymerization apparatus equipped with a stirrer.
Deionized water: 175 parts by mass Polyoxyethylene lauryl ether phosphoric acid: 0.104 parts by mass Boric acid: 0.4725 parts by mass Sodium carbonate: 0.04725 parts by mass
　重合機内を窒素ガスで充分に置換した後、内温を８０℃にし、モノマー混合物（１－１）２７質量部（メタクリル酸メチル７０．９質量％、アクリル酸ブチル１２．５質量％、スチレン１６．６質量％）およびメタクリル酸アリル０．１３５質量部からなる混合物の２６質量％を重合機に一括で追加し、その後、ソディウムホルムアルデヒドスルフォキシレート０．０６４５質量部、エチレンジアミン四酢酸－２－ナトリウム０．００５６質量部、硫酸第一鉄０．００１４質量部、ｔ－ブチルハイドロパーオキサイド０．０２０７質量部を追加し、その１５分後にｔ－ブチルハイドロパーオキサイド０．０３４５質量部を追加し、さらに１５分重合を継続させた。
　次に、水酸化ナトリウム０．００９８質量部を２質量％水溶液の形態で、ポリオキシエチレンラウリルエーテルリン酸０．０８５２質量部をそのまま追加し、上記混合物の残り７４質量％を６０分かけて連続的に添加した。添加終了３０分後に、ｔ－ブチルハイドロパーオキサイド０．０６９質量部を追加し、さらに３０分重合を継続することにより、重合物を得た。 After sufficiently replacing the inside of the polymerization machine with nitrogen gas, the internal temperature was adjusted to 80 ° C., 27 parts by mass of the monomer mixture (1-1) (70.9% by mass of methyl methacrylate, 12.5% by mass of butyl acrylate, 16 styrene). .6% by mass) and 26% by mass of the mixture consisting of 0.135 parts by mass of allyl methacrylate were added to the polymerization machine in a batch, and then 0.0645 parts by mass of sodium formaldehyde sulfoxylate and 0.135 parts by mass of ethylenediamine tetraacetic acid-2- 0.0056 parts by mass of sodium, 0.0014 parts by mass of ferrous sulfate, and 0.0207 parts by mass of t-butyl hydropolymer were added, and 15 minutes later, 0.0345 parts by mass of t-butyl hydropolymer was added. , The polymerization was continued for another 15 minutes.
Next, 0.0098 parts by mass of sodium hydroxide was added as it was in the form of a 2% by mass aqueous solution, and 0.0852 parts by mass of polyoxyethylene lauryl ether phosphoric acid was added as it was, and the remaining 74% by mass of the mixture was continuously added over 60 minutes. Was added. After 30 minutes from the completion of the addition, 0.069 parts by mass of t-butyl hydroperoxide was added, and the polymerization was continued for another 30 minutes to obtain a polymer.
　その後、水酸化ナトリウム０．０２６７質量部を２質量％水溶液の形態で、過硫酸カリウム０．０８質量部を２質量％水溶液の形態で添加し、次いで、モノマー混合物（１－２）（アクリル酸ブチル４７．０質量％、スチレン５３．０質量％）５０質量部およびメタクリル酸アリル０．７５質量部からなる混合物を１５０分かけて連続的に添加した。添加終了後、過硫酸カリウム０．０１５質量部を２質量％水溶液の形態で添加し、１２０分重合を継続し、アクリル系ゴム状重合体を得た。得られたアクリル系ゴム状重合体の全構造単位（モノマー混合物（１－１）と（１－２）の合計）に対する、スチレンに由来する構造単位の含有量（質量％）は、４０質量％であった。 Then, 0.0267 parts by mass of sodium hydroxide was added in the form of a 2% by mass aqueous solution, and 0.08 parts by mass of potassium persulfate was added in the form of a 2% by mass aqueous solution, and then the monomer mixture (1-2) (acrylic acid) was added. A mixture consisting of 50 parts by mass of butyl (47.0% by mass, 53.0% by mass of styrene) and 0.75 parts by mass of allyl methacrylate was continuously added over 150 minutes. After completion of the addition, 0.015 parts by mass of potassium persulfate was added in the form of a 2% by mass aqueous solution, and the polymerization was continued for 120 minutes to obtain an acrylic rubber-like polymer. The content (% by mass) of the structural unit derived from styrene with respect to the total structural unit (total of the monomer mixture (1-1) and (1-2)) of the obtained acrylic rubber-like polymer is 40% by mass. Met.
　その後、過硫酸カリウム０．０２３質量部を２質量％水溶液の形態で添加し、モノマー混合物（２－１）１５質量部（メタクリル酸メチル９５質量％、アクリル酸ブチル５質量％）を４５分かけて連続的に添加し、さらに３０分重合を継続した。 Then, 0.023 parts by mass of potassium persulfate was added in the form of a 2% by mass aqueous solution, and 15 parts by mass (95% by mass of methyl methacrylate, 5% by mass of butyl acrylate) of the monomer mixture (2-1) was applied over 45 minutes. Was added continuously, and the polymerization was continued for another 30 minutes.
　その後、モノマー混合物（２－２）８質量部（メタクリル酸メチル５２質量％、アクリル酸ブチル４８質量％）を２５分かけて連続的に添加し、さらに６０分重合を継続することにより、グラフト共重合体ラテックスを得た。 Then, 8 parts by mass (52% by mass of methyl methacrylate, 48% by mass of butyl acrylate) of the monomer mixture (2-2) was continuously added over 25 minutes, and the polymerization was continued for another 60 minutes to carry out the graft copolymerization. A polymer latex was obtained.
　得られたラテックスを塩化マグネシウムで塩析、凝固し、水洗、乾燥を行い、白色粉末状のグラフト共重合体（ゴム粒子Ｒ１）を得た。ゴム粒子Ｒ１のグラフト率は２４．２％であり、スチレン量は４０質量％、ガラス転移温度（Ｔｇ）は５℃、平均粒子径は２００ｎｍであった。 The obtained latex was salted out with magnesium chloride, solidified, washed with water, and dried to obtain a white powdery graft copolymer (rubber particles R1). The graft ratio of the rubber particles R1 was 24.2%, the amount of styrene was 40% by mass, the glass transition temperature (Tg) was 5 ° C., and the average particle size was 200 nm.
　＜ゴム粒子Ｒ２～Ｒ５の調製＞
　アクリル系ゴム状重合体を構成する全構造単位に対するスチレンに由来する構造単位の含有量（質量％）が表２に示される値となるように、モノマー混合物（１－１）と（１－２）のモノマー組成を変更した以外はゴム粒子Ｒ１と同様にしてグラフト共重合体（ゴム粒子）を得た。 <Preparation of rubber particles R2 to R5>
The monomer mixture (1-1) and (1-2) so that the content (% by mass) of the structural unit derived from styrene with respect to all the structural units constituting the acrylic rubber-like polymer is the value shown in Table 2. A graft copolymer (rubber particles) was obtained in the same manner as the rubber particles R1 except that the monomer composition of) was changed.
　ゴム粒子Ｒ１～Ｒ５の構成を、表２に示す。
Figure JPOXMLDOC01-appb-T000002
 The configurations of the rubber particles R1 to R5 are shown in Table 2.
Figure JPOXMLDOC01-appb-T000002
　ゴム粒子Ｒ１～Ｒ５の平均粒子径は、以下の方法で測定した。 The average particle size of the rubber particles R1 to R5 was measured by the following method.
　（平均粒子径）
　得られた分散液中のゴム粒子の分散粒径を、ゼータ電位・粒径測定システム（大塚電子株式会社製　ＥＬＳＺ－２０００ＺＳ）で測定した。 (Average particle size)
The dispersed particle size of the rubber particles in the obtained dispersion was measured by a zeta potential / particle size measuring system (ELSZ-2000ZS manufactured by Otsuka Electronics Co., Ltd.).
　（スチレン量）
　ゴム粒子のスチレン類に由来する構造単位の含有量は、前述の熱分解ＧＣ／ＭＳにより検出されるピークの面積比から算出する方法により測定した。なお、ＧＣＭＳの測定条件は、以下の通りとした。
　測定装置：ＳＨＩＭＡＺＵ　ＧＣＭＳ　ＱＰ２０１０
　カラム種：Ｕｒｔｒａ　Ａｌｌｏｙ－５（サイズ３０ｍ×径０．２５ｍｍ）
　キャリアガス種：Ｈｅ
　流量条件：１．８ｍＬ／分
　カラムオーブン温度条件：４０℃－１０℃／分－３２０℃
　インターフェイス温度：３００℃
　イオン源温度：２００℃
　検出モード：ＳＩＭ（ターゲットイオン：ｍ／ｚ１０４、確認イオン：ｍ／ｚ７８） (Amount of styrene)
The content of the structural unit derived from styrenes of the rubber particles was measured by the method calculated from the area ratio of the peak detected by the above-mentioned thermal decomposition GC / MS. The measurement conditions for GCMS were as follows.
Measuring device: SHIMAZU GCMS QP2010
Column type: Ultra Alloy-5 (size 30 m x diameter 0.25 mm)
Carrier gas type: He
Flow rate condition: 1.8 mL / min Column oven temperature condition: 40 ° C-10 ° C / min-320 ° C
Interface temperature: 300 ° C
Ion source temperature: 200 ° C
Detection mode: SIM (target ion: m / z104, confirmed ion: m / z78)
　２．保護フィルムの作製
　２－１．保護フィルムＡの作製
　＜保護フィルム１０１の作製＞
　（メタ）アクリル系樹脂１のペレットとゴム粒子Ｒ１とを、乾燥機にて８０℃で４時間乾燥させた後、φ６５ｍｍ単軸押出機に供給した。押出機出口で樹脂温度が２７０℃となるように加熱溶融し、Ｔダイから溶融樹脂を押し出した。Ｔダイ出口における３吐出直後の樹脂温度は２７０℃であった。吐出された溶融樹脂を、７０℃に調整したキャストロールと７０℃に調整したタッチロールとで挟み込み、冷却固化した。その後、得られたフィルムの両端を連続的にスリットした後、引き取りロールで引き取りながら巻き取り、厚み５５μｍの保護フィルム１０１を得た。 2. Preparation of protective film 2-1. Preparation of protective film A <Production of protective film 101>
The pellet of the (meth) acrylic resin 1 and the rubber particles R1 were dried at 80 ° C. for 4 hours in a dryer and then supplied to a φ65 mm single-screw extruder. The molten resin was extruded from the T-die by heating and melting at the extruder outlet so that the resin temperature became 270 ° C. The resin temperature immediately after 3 discharges at the T-die outlet was 270 ° C. The discharged molten resin was sandwiched between a cast roll adjusted to 70 ° C. and a touch roll adjusted to 70 ° C., and cooled and solidified. Then, after continuously slitting both ends of the obtained film, the film was wound while being taken up by a take-up roll to obtain a protective film 101 having a thickness of 55 μm.
　＜保護フィルム１０２の作製＞
　冷却固化後に得られたフィルムを、表３に示される条件で延伸した以外は保護フィルム１０１と同様にして保護フィルム１０２を得た。 <Preparation of protective film 102>
A protective film 102 was obtained in the same manner as the protective film 101 except that the film obtained after cooling and solidification was stretched under the conditions shown in Table 3.
　＜保護フィルム１０３の作製＞
　ゴム粒子Ｒ１を添加せず、かつ表３に示される条件で延伸した以外は保護フィルム１０１と同様の方法で保護フィルム１０３を得た。 <Preparation of protective film 103>
A protective film 103 was obtained in the same manner as the protective film 101 except that the rubber particles R1 were not added and the film was stretched under the conditions shown in Table 3.
　＜保護フィルム１０４の作製＞
　（ゴム粒子分散液の調製）
　１１．３質量部のゴム粒子Ｒ２と、２００質量部のメチレンクロライドとを、ディゾルバーで５０分間撹拌混合した後、マイルダー分散機（大平洋機工株式会社製）を用いて１５００ｒｐｍ条件下で分散し、ゴム粒子分散液を得た。 <Preparation of protective film 104>
(Preparation of rubber particle dispersion)
11.3 parts by mass of rubber particles R2 and 200 parts by mass of methylene chloride were stirred and mixed with a dissolver for 50 minutes, and then dispersed under a condition of 1500 rpm using a milder disperser (manufactured by Pacific Machinery & Engineering Co., Ltd.). A rubber particle dispersion was obtained.
　（ドープの調製）
　次いで、下記組成のドープを調製した。まず、加圧溶解タンクにメチレンクロライド、およびエタノールを添加した。次いで、加圧溶解タンクに、（メタ）アクリル系樹脂２を撹拌しながら投入した。次いで、上記調製したゴム粒子分散液を投入して、これを撹拌しながら、完全に溶解させた。これを、（株）ロキテクノ製のＳＨＰ１５０を使用して濾過し、ドープを得た。
　（メタ）アクリル系樹脂２：１００質量部
　メチレンクロライド：２００質量部
　エタノール：１００質量部
　ゴム粒子分散液：５００質量部 (Preparation of doping)
Then, a dope having the following composition was prepared. First, methylene chloride and ethanol were added to the pressurized dissolution tank. Next, the (meth) acrylic resin 2 was charged into the pressure dissolution tank with stirring. Then, the rubber particle dispersion liquid prepared above was added, and this was completely dissolved while stirring. This was filtered using SHP150 manufactured by Roki Techno Co., Ltd. to obtain a doping.
(Meta) Acrylic resin 2: 100 parts by mass Methylene chloride: 200 parts by mass Ethanol: 100 parts by mass Rubber particle dispersion: 500 parts by mass
　（製膜）
　無端ベルト流延装置を用い、ドープを温度３０℃、１８００ｍｍ幅でステンレスベルト支持体上に均一に流延した。ステンレスベルトの温度は２８℃に制御した。ステンレスベルトの搬送速度は２０ｍ／ｍｉｎとした。 (Film formation)
The dope was uniformly cast on the stainless belt support at a temperature of 30 ° C. and a width of 1800 mm using an endless belt casting device. The temperature of the stainless steel belt was controlled to 28 ° C. The transport speed of the stainless steel belt was 20 m / min.
　ステンレスベルト支持体上で、流延（キャスト）したドープ中の残留溶媒量が３０質量％になるまで溶媒を蒸発させた。次いで、剥離張力１２８Ｎ／ｍで、ステンレスベルト支持体から剥離し、膜状物を得た。つまり、剥離時の膜状物の残留溶媒量は３０質量％であった。剥離したフィルムを多数のローラーで搬送させながら、さらに乾燥させて、膜厚５５μｍの保護フィルム１０４を得た。 The solvent was evaporated on the stainless belt support until the amount of residual solvent in the cast dope reached 30% by mass. Then, it was peeled from the stainless belt support at a peeling tension of 128 N / m to obtain a film-like material. That is, the amount of residual solvent in the film-like substance at the time of peeling was 30% by mass. The peeled film was further dried while being conveyed by a large number of rollers to obtain a protective film 104 having a film thickness of 55 μm.
　＜保護フィルム１０５および１０６の作製＞
　ゴム粒子Ｒ１の含有量を表３に示されるように変更した以外は保護フィルム１０１と同様にして保護フィルム１０５および１０６を得た。 <Preparation of protective films 105 and 106>
Protective films 105 and 106 were obtained in the same manner as the protective film 101 except that the content of the rubber particles R1 was changed as shown in Table 3.
　＜保護フィルム１０７および１０８の作製＞
　保護フィルムの厚みが表３に示される値となるように吐出量を調整した以外は保護フィルム１０１と同様にして保護フィルム１０７および１０８を得た。 <Preparation of protective films 107 and 108>
Protective films 107 and 108 were obtained in the same manner as the protective film 101 except that the discharge amount was adjusted so that the thickness of the protective film became the value shown in Table 3.
　＜評価＞
　得られた保護フィルム１０１～１０８におけるゴム粒子の平均アスペクト比および引張弾性率を、以下の方法で測定した。 <Evaluation>
The average aspect ratio and tensile elastic modulus of the rubber particles in the obtained protective films 101 to 108 were measured by the following methods.
　（平均アスペクト比、平均長径）
　ゴム粒子の平均アスペクト比および平均長径は、以下の手順で算出した。
　１）保護フィルムの厚み方向に沿った断面のうち、保護フィルムのＴＤ方向と平行な断面をＴＥＭ観察した。観察領域は、５μｍ×５μｍとした。
　２）得られたＴＥＭ画像における、各ゴム粒子の長径および短径をそれぞれ測定し、アスペクト比をそれぞれ算出した。
　３）上記１）および２）の操作を、観察領域を変えて合計４箇所行った。そして、測定されたアスペクト比の平均値を「平均アスペクト比」とし、測定された長径の平均値を「平均長径」とした。 (Average aspect ratio, average major axis)
The average aspect ratio and average major axis of the rubber particles were calculated by the following procedure.
1) Of the cross sections along the thickness direction of the protective film, the cross section parallel to the TD direction of the protective film was observed by TEM. The observation area was 5 μm × 5 μm.
2) In the obtained TEM image, the major axis and the minor axis of each rubber particle were measured, and the aspect ratio was calculated.
3) The above operations 1) and 2) were performed at a total of 4 locations with different observation areas. Then, the average value of the measured aspect ratios was defined as the "average aspect ratio", and the average value of the measured major axes was defined as the "average major axis".
　（引張弾性率）
　得られた保護フィルムを、１ｃｍ（ＴＤ方向）×１０ｃｍ（ＭＤ方向）に切り出して試料片とし、２５℃６０％ＲＨの環境下で２４時間調湿した。得られた試料片の引張弾性率を、ＪＩＳ　Ｋ７１２７に記載の引張り試験方法により測定した。具体的には、試料片を、引張試験装置オリエンテック社製テンシロンにセットし、チャック間距離５０．０ｍｍ、引張り速度５０ｍｍ／ｍｉｎの条件で引張試験を行ったときの引張弾性率を測定した。測定は、２５℃６０％ＲＨ下で行った。 (Tensile modulus)
The obtained protective film was cut into 1 cm (TD direction) × 10 cm (MD direction) to prepare a sample piece, and the humidity was adjusted for 24 hours in an environment of 25 ° C. and 60% RH. The tensile elastic modulus of the obtained sample piece was measured by the tensile test method described in JIS K7127. Specifically, the sample piece was set in a Tensilon manufactured by Orientec Co., Ltd., and the tensile elastic modulus was measured when the tensile test was performed under the conditions of a distance between chucks of 50.0 mm and a tensile speed of 50 mm / min. The measurement was performed at 25 ° C. and 60% RH.
　保護フィルム１０１～１０８の評価結果を表３に示す。なお、表３中のゴム粒子の含有量は、保護フィルムに対する量を示す。表４および５も同様である。 Table 3 shows the evaluation results of the protective films 101 to 108. The content of the rubber particles in Table 3 indicates the amount with respect to the protective film. The same applies to Tables 4 and 5.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　２－２．保護フィルムＢの作製
　＜保護フィルム２０１の作製＞
　（ゴム粒子分散液の調製）
　１１質量部のゴム粒子Ｒ３と、２００質量部のメチレンクロライドとを、ディゾルバーで５０分間撹拌混合した後、マイルダー分散機マイルダー分散機（大平洋機工株式会社製）を用いて１５００ｒｐｍ条件下で分散し、ゴム粒子分散液を得た。 2-2. Preparation of protective film B <Production of protective film 201>
(Preparation of rubber particle dispersion)
11 parts by mass of rubber particles R3 and 200 parts by mass of methylene chloride were stirred and mixed with a dissolver for 50 minutes, and then dispersed under 1500 rpm conditions using a milder disperser milder disperser (manufactured by Pacific Machinery & Engineering Co., Ltd.). , A rubber particle dispersion was obtained.
　（ドープの調製）
　次いで、下記組成のドープを調製した。まず、加圧溶解タンクにメチレンクロライド、およびエタノールを添加した。次いで、加圧溶解タンクに、（メタ）アクリル系樹脂を撹拌しながら投入した。次いで、上記調製したゴム粒子分散液を投入して、これを撹拌しながら、完全に溶解させた。これを、（株）ロキテクノ製のＳＨＰ１５０を使用して濾過し、ドープを得た。
　（メタ）アクリル系樹脂３：１００質量部
　メチレンクロライド：４００質量部
　エタノール：９０質量部
　ゴム粒子分散液：２２０質量部 (Preparation of doping)
Then, a dope having the following composition was prepared. First, methylene chloride and ethanol were added to the pressurized dissolution tank. Next, the (meth) acrylic resin was charged into the pressure dissolution tank with stirring. Then, the rubber particle dispersion liquid prepared above was added, and this was completely dissolved while stirring. This was filtered using SHP150 manufactured by Roki Techno Co., Ltd. to obtain a doping.
(Meta) Acrylic resin 3: 100 parts by mass Methylene chloride: 400 parts by mass Ethanol: 90 parts by mass Rubber particle dispersion: 220 parts by mass
　（製膜）
　無端ベルト流延装置を用い、ドープを温度３０℃、１８００ｍｍ幅でステンレスベルト支持体上に均一に流延した。ステンレスベルトの温度は２８℃に制御した。ステンレスベルトの搬送速度は２０ｍ／ｍｉｎとした。 (Film formation)
The dope was uniformly cast on the stainless belt support at a temperature of 30 ° C. and a width of 1800 mm using an endless belt casting device. The temperature of the stainless steel belt was controlled to 28 ° C. The transport speed of the stainless steel belt was 20 m / min.
　ステンレスベルト支持体上で、流延（キャスト）したドープ中の残留溶媒量が３０質量％になるまで溶媒を蒸発させた。次いで、剥離張力１２８Ｎ／ｍで、ステンレスベルト支持体から剥離し、膜状物を得た。剥離時の膜状物の残留溶媒量は３０質量％であった。 The solvent was evaporated on the stainless belt support until the amount of residual solvent in the cast dope reached 30% by mass. Then, it was peeled from the stainless belt support at a peeling tension of 128 N / m to obtain a film-like material. The amount of residual solvent in the film-like material at the time of peeling was 30% by mass.
　次いで、剥離したフィルムを多数のローラーで搬送させながら、得られた膜状物を、テンターにて６０℃（Ｔｇ－６０℃）の条件下で幅方向（ＴＤ方向）に７０％延伸した。その後、ロールで搬送しながら、１４０℃（Ｔｇ＋４０℃）でさらに乾燥させ、テンタークリップで挟んだ端部をレーザーカッターでスリットして巻き取り、膜厚２０μｍの保護フィルム２０１を得た。 Next, while transporting the peeled film with a large number of rollers, the obtained film-like material was stretched by 70% in the width direction (TD direction) under the condition of 60 ° C. (Tg-60 ° C.) with a tenter. Then, the film was further dried at 140 ° C. (Tg + 40 ° C.) while being conveyed by a roll, and the end portion sandwiched between the tenter clips was slit with a laser cutter and wound up to obtain a protective film 201 having a film thickness of 20 μm.
　＜保護フィルム２０２～２０５の作製＞
　延伸条件を、表４に示されるように変更した以外は保護フィルム２０１と同様にして保護フィルム２０２～２０５を得た。 <Making protective films 202-205>
Protective films 202 to 205 were obtained in the same manner as the protective film 201 except that the stretching conditions were changed as shown in Table 4.
　＜保護フィルム２０６の作製＞
　ゴム粒子Ｒ３を添加せず、かつ延伸条件を表４に示されるように変更した以外は保護フィルム２０１と同様にして保護フィルム２０６を得た。 <Preparation of protective film 206>
A protective film 206 was obtained in the same manner as the protective film 201 except that the rubber particles R3 were not added and the stretching conditions were changed as shown in Table 4.
　＜保護フィルム２０７～２１２の作製＞
　（メタ）アクリル系樹脂の種類を表４に示されるように変更した以外は保護フィルム２０１と同様にして保護フィルム２０７～２１２を得た。なお、保護フィルム２０７については、延伸条件も表４に示されるように変更した。 <Manufacturing of protective films 207 to 212>
Protective films 207 to 212 were obtained in the same manner as the protective film 201 except that the type of the (meth) acrylic resin was changed as shown in Table 4. Regarding the protective film 207, the stretching conditions were also changed as shown in Table 4.
　＜保護フィルム２１３、２１４の作製＞
　ゴム粒子の種類を表４に示されるように変更した以外は保護フィルム２０１と同様にして保護フィルム２１３、２１４を得た。 <Preparation of protective films 213 and 214>
Protective films 213 and 214 were obtained in the same manner as the protective film 201 except that the types of rubber particles were changed as shown in Table 4.
　＜保護フィルム２１５および２１６の作製＞
　得られる保護フィルムの厚みが表４に示される値となるように流延量を調整した以外は保護フィルム２０１と同様にして保護フィルム２１５および２１６を得た。 <Preparation of protective films 215 and 216>
Protective films 215 and 216 were obtained in the same manner as the protective film 201 except that the casting amount was adjusted so that the thickness of the obtained protective film became the value shown in Table 4.
　＜評価＞
　得られた保護フィルム２０１～２１６における、ゴム粒子の平均アスペクト比および引張弾性率を、それぞれ前述と同様の方法で測定した。保護フィルム２０１～２１６の評価結果を表４に示す。なお、保護フィルム２０１に含まれるゴム粒子の平均長径は、３６０ｎｍであった。 <Evaluation>
The average aspect ratio and tensile elastic modulus of the rubber particles in the obtained protective films 201 to 216 were measured by the same methods as described above. The evaluation results of the protective films 201 to 216 are shown in Table 4. The average major axis of the rubber particles contained in the protective film 201 was 360 nm.
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　３．偏光板の作製と評価
　＜偏光板３０１の作製＞
　（偏光子の作製）
　厚さ２５μｍのポリビニルアルコール系フィルムを、３５℃の水で膨潤させた。得られたフィルムを、ヨウ素０．０７５ｇ、ヨウ化カリウム５ｇおよび水１００ｇからなる水溶液に６０秒間浸漬し、さらにヨウ化カリウム３ｇ、ホウ酸７．５ｇおよび水１００ｇからなる４５℃の水溶液に浸漬した。得られたフィルムを、延伸温度５５℃、延伸倍率５倍の条件で一軸延伸した。この一軸延伸フィルムを、水洗した後、乾燥させて、厚み１２μｍの偏光子を得た。 3. 3. Fabrication and evaluation of polarizing plate <Preparation of polarizing plate 301>
(Making a polarizer)
A polyvinyl alcohol-based film having a thickness of 25 μm was swollen with water at 35 ° C. The obtained film was immersed in an aqueous solution consisting of 0.075 g of iodine, 5 g of potassium iodide and 100 g of water for 60 seconds, and further immersed in an aqueous solution of 45 ° C. consisting of 3 g of potassium iodide, 7.5 g of boric acid and 100 g of water. .. The obtained film was uniaxially stretched under the conditions of a stretching temperature of 55 ° C. and a stretching ratio of 5 times. This uniaxially stretched film was washed with water and then dried to obtain a polarizer having a thickness of 12 μm.
　（紫外線硬化性接着剤組成物の調製）
　下記成分を混合した後、脱泡して、紫外線硬化性接着剤組成物を調製した。
　３，４－エポキシシクロヘキシルメチル－３，４－エポキシシクロヘキサンカルボキシレート：４５質量部
　エポリードＧＴ－３０１（ダイセル社製の脂環式エポキシ樹脂）：４０質量部
　１，４－ブタンジオールジグリシジルエーテル：１５質量部
　トリアリールスルホニウムヘキサフルオロホスフェート：２．３質量部（固形分）
　９，１０－ジブトキシアントラセン：０．１質量部
　１，４－ジエトキシナフタレン：２．０質量部
　なお、トリアリールスルホニウムヘキサフルオロホスフェートは、５０％プロピレンカーボネート溶液として配合した。 (Preparation of UV curable adhesive composition)
After mixing the following components, defoaming was performed to prepare an ultraviolet curable adhesive composition.
3,4-Epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate: 45 parts by mass Epolide GT-301 (alicyclic epoxy resin manufactured by Daicel): 40 parts by mass 1,4-butanediol diglycidyl ether: 15 parts by mass Parts by mass Triarylsulfonium hexafluorophosphate: 2.3 parts by mass (solid content)
9,10-Dibutoxyanthracene: 0.1 parts by mass 1,4-diethoxynaphthalene: 2.0 parts by mass Triarylsulfonium hexafluorophosphate was blended as a 50% propylene carbonate solution.
　（偏光板の作製）
　上記作製した保護フィルム１０１の表面に、コロナ出力強度２．０ｋＷ、ライン速度１８ｍ／分でコロナ放電処理を施した。次いで、保護フィルム１０１のコロナ放電処理面に、上記調製した紫外線硬化性接着剤組成物を、硬化後の膜厚が約３μｍとなるようにバーコーターで塗布して、紫外線硬化性接着剤層を形成した。
　同様に、上記作製した保護フィルム２０１の表面にコロナ放電処理を施した後、上記調製した紫外線硬化性接着剤組成物を、硬化後の膜厚が３μｍとなるように塗布して、紫外線硬化性接着剤層を形成した。 (Preparation of polarizing plate)
The surface of the protective film 101 produced above was subjected to a corona discharge treatment at a corona output strength of 2.0 kW and a line speed of 18 m / min. Next, the UV-curable adhesive composition prepared above was applied to the corona discharge-treated surface of the protective film 101 with a bar coater so that the film thickness after curing was about 3 μm to form a UV-curable adhesive layer. Formed.
Similarly, after the surface of the protective film 201 produced above is subjected to a corona discharge treatment, the above-prepared UV-curable adhesive composition is applied so that the cured film thickness is 3 μm, and the UV-curable adhesive composition is applied. An adhesive layer was formed.
　次いで、上記作製した偏光子の一方の面に、紫外線硬化性接着剤層を介して保護フィルム１０１を配置し、他方の面に、紫外線硬化性接着剤層を介して保護フィルム２０１を配置して、積層物を得た。積層は、偏光子の吸収軸と、保護フィルムの遅相軸とが直交するように行った。 Next, the protective film 101 is arranged on one surface of the produced polarizing element via the ultraviolet curable adhesive layer, and the protective film 201 is arranged on the other surface via the ultraviolet curable adhesive layer. , Obtained a laminate. Lamination was performed so that the absorption axis of the polarizer and the slow axis of the protective film were orthogonal to each other.
　次いで、得られた積層物に、ベルトコンベヤー付き紫外線照射装置（ランプは、フュージョンＵＶシステムズ社製のＤバルブを使用）を用いて、積算光量が７５０ｍＪ／ｃｍ２となるように紫外線を照射し、紫外線硬化性接着剤層を硬化させた。 Next, the obtained laminate was irradiated with ultraviolet rays so that the integrated light amount was 750 mJ / cm 2 using an ultraviolet irradiation device with a belt conveyor (the lamp uses a D bulb manufactured by Fusion UV Systems). The UV curable adhesive layer was cured.
　そして、得られた積層の保護フィルムＢ上に、下記粘着剤層付きＰＥＴフィルムの粘着剤層（厚み２０μｍ）を貼り合わせた。それにより、保護フィルム１０１（保護フィルムＡ）／接着剤層／偏光子／接着剤層／保護フィルム２０１（保護フィルムＢ）／粘着剤層／ＰＥＴフィルムの積層構造を有する偏光板３０１を得た。なお、粘着剤層は、（メタ）アクリル系ポリマーと架橋剤とを含むアクリル系粘着剤組成物を、ＰＥＴフィルム上に塗布した後、加熱乾燥（部分架橋）させたものである。 Then, the adhesive layer (thickness 20 μm) of the following PET film with an adhesive layer was bonded onto the obtained laminated protective film B. As a result, a polarizing plate 301 having a laminated structure of protective film 101 (protective film A) / adhesive layer / polarizer / adhesive layer / protective film 201 (protective film B) / adhesive layer / PET film was obtained. The pressure-sensitive adhesive layer is obtained by applying an acrylic pressure-sensitive adhesive composition containing a (meth) acrylic polymer and a cross-linking agent onto a PET film and then heat-drying (partially cross-linking) the pressure-sensitive adhesive layer.
　＜偏光板３０２～３２３の作製＞
　保護フィルムＡおよびＢを、表５に示されるように変更した以外は偏光板３０１と同様にして偏光板３０２～３２３を得た。 <Preparation of polarizing plates 302 to 323>
Polarizing plates 302 to 323 were obtained in the same manner as the polarizing plate 301 except that the protective films A and B were changed as shown in Table 5.
　＜評価＞
　得られた偏光板の打ち抜き性および（打鍵試験後の）表示ムラを、以下の方法で測定した。 <Evaluation>
The punching property of the obtained polarizing plate and the display unevenness (after the keystroke test) were measured by the following methods.
　（打ち抜き性）
　図３ＡおよびＢは、実施例における偏光板１００の打ち抜き工程を示す図である。図３Ａは、偏光板１００の斜視図であり、図３Ｂは、Ａ－Ａ線の部分断面図である。 (Punchability)
3A and 3B are diagrams showing a punching process of the polarizing plate 100 in the examples. FIG. 3A is a perspective view of the polarizing plate 100, and FIG. 3B is a partial cross-sectional view taken along the line AA.
　図３ＡおよびＢに示されるように、得られた偏光板１００を、粘着剤層１４０を介してＰＥＴフィルム１７０上に貼り合わせた。そして、ＰＥＴフィルム１７０に貼り合わせた偏光板１００を、図３Ａに示されるように、１ｍ角の偏光板１００（図３ＡのＷが１ｍ）を、１０ｃｍ角の正方形に９枚打ち抜いた。隣り合う偏光板同士の隙間ｐは、１ｃｍとした。 As shown in FIGS. 3A and 3B, the obtained polarizing plate 100 was bonded onto the PET film 170 via the pressure-sensitive adhesive layer 140. Then, as shown in FIG. 3A, nine 1 m square polarizing plates 100 (W in FIG. 3A is 1 m) were punched out into a 10 cm square square plate 100 bonded to the PET film 170. The gap p between adjacent polarizing plates was set to 1 cm.
　打ち抜いた９枚の偏光板を光学顕微鏡にて観察し、発生したクラックの個数および剥がれをカウントして平均を算出した。そして、以下の評価基準に基づき、打ち抜き性を評価した。
　◎：クラック、剥がれともに観察されない
　○：クラックまたは剥がれが２箇所以下で発生
　○△：クラックまたは剥がれが３～５箇所で発生
　△：クラックおよび剥がれがそれぞれ３～５箇所で発生
　×：クラックおよび剥がれがそれぞれ６箇所以上で発生
　○△、○および◎が実用上許容されるレベルである。 The nine punched polarizing plates were observed with an optical microscope, and the number of cracks generated and the peeling were counted to calculate the average. Then, the punching property was evaluated based on the following evaluation criteria.
⊚: Neither crack nor peeling is observed ○: Crack or peeling occurs at 2 or less places ○ △: Crack or peeling occurs at 3 to 5 places △: Crack and peeling occur at 3 to 5 places respectively ×: Crack and peeling occur Are generated at 6 or more locations, respectively. ○ △, ○, and ◎ are practically acceptable levels.
　（表示ムラ）
　（１）タッチパネル部材を有する液晶表示装置の作製
　タッチパネル部材を有する液晶表示装置であるＳＯＮＹ社製２１．５インチＶＡＩＯＴａｐ２１（ＳＶＴ２１２１９ＤＪＢ）から、予め貼り合わされていた２枚の偏光板を剥がして、上記作製した偏光板をそれぞれ貼り合わせて、タッチパネル部材を有する液晶表示装置を得た。偏光板の貼り合わせは、ＰＥＴフィルムを剥がし取り、露出した粘着剤層が液晶セルに密着するように行った。 (Display unevenness)
(1) Manufacture of a liquid crystal display device having a touch panel member The two polarizing plates previously bonded to each other are peeled off from a 21.5-inch VAIOTap21 (SVT21219DJB) manufactured by SONY, which is a liquid crystal display device having a touch panel member, and the above-mentioned production is performed. A liquid crystal display device having a touch panel member was obtained by laminating the polarizing plates. The polarizing plate was attached by peeling off the PET film so that the exposed adhesive layer adhered to the liquid crystal cell.
　（２）打鍵試験
　得られた液晶表示装置を、４０℃・９５％ＲＨに制御された可変空調室内（朝日科学（株）製ＡＥＳ－２００）にて、３００時間放置した。その後、同環境下において打鍵試験機２０２型－９５０－２（株式会社タッチパネル研究所製）を用いて、打鍵速度を２Ｈｚ、荷重１５０ｇの条件で、カバーガラス側の上方から入力ペンを１万５０００回押し当てた。なお、入力ペンのペン先材料は、ゴム下に敷く測定盤をガラス基板とし、その上に、導電メッシュがガラス側になるようにして置き、上方から入力ペンを３００ｇ荷重で押し当て、摺動距離５ｃｍ、往復１秒（５ｃｍを１秒間で往復）の条件で繰り返し摺動させた。なお、入力ペンのペン先材料はポリアセタールであり、Ｒは０．８ｍｍである。 (2) Keystroke test The obtained liquid crystal display device was left to stand for 300 hours in a variable air conditioning room (AES-200 manufactured by Asahi Kagaku Co., Ltd.) controlled at 40 ° C. and 95% RH. After that, in the same environment, using a keystroke tester 202 type-950-2 (manufactured by Touch Panel Laboratory Co., Ltd.), the input pen was inserted from above the cover glass side under the conditions of a keystroke speed of 2 Hz and a load of 150 g. I pressed it twice. As the pen tip material of the input pen, the measuring board laid under the rubber is used as a glass substrate, the conductive mesh is placed on the glass substrate, and the input pen is pressed from above with a load of 300 g and slides. The glass was repeatedly slid under the conditions of a distance of 5 cm and a reciprocation of 1 second (5 cm reciprocating in 1 second). The pen tip material of the input pen is polyacetal, and R is 0.8 mm.
　（３）表示ムラ 
　打鍵試験後の液晶表示装置を、４０℃・９５％ＲＨの環境下にて３００時間放置した。次いで、４０℃・ｄｒｙ環境下に２時間置き、その後、２３℃・５５％ＲＨ環境下で２４時間点灯させた後に、表示パネル正面から表示ムラを観察した。表示ムラは、以下の基準に基づいて評価した。
　◎：表示パネルのムラが認識できない
　○：表示パネルにムラがごく微少に見られるが品質上影響ない
　○△：表示パネルに局所的なムラが見られるが、ムラの部分とそうでない部分の境界が視認できない
　△：表示パネルに局部的なムラが見られ、ムラの部分とそうでない部分が境界が視認できる
　×：表示パネル全面にムラが見られ、ムラの部分とそうでない部分が明確に視認できる   
　○△、○および◎が実用上許容されるレベルである。 (3) Display unevenness
The liquid crystal display device after the keystroke test was left for 300 hours in an environment of 40 ° C. and 95% RH. Then, it was left in a 40 ° C. / dry environment for 2 hours, and then turned on for 24 hours in a 23 ° C./55% RH environment, and then display unevenness was observed from the front of the display panel. Display unevenness was evaluated based on the following criteria.
◎: Unable to recognize unevenness on the display panel ○: Very slight unevenness on the display panel does not affect the quality ○ △: Local unevenness is seen on the display panel, but the boundary between the uneven part and the non-uneven part Is not visible △: Local unevenness is seen on the display panel, and the boundary between the uneven part and the non-uneven part can be seen. ×: The uneven part is seen on the entire surface of the display panel, and the uneven part and the non-uneven part are clearly visible. it can
○ △, ○ and ◎ are practically acceptable levels.
　得られた偏光板３０１～３２３の構成と評価結果を、表５に示す。 Table 5 shows the configurations and evaluation results of the obtained polarizing plates 301 to 323.
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
　表５に示されるように、偏光板３０１～３０３、３１０～３１２および３１５～３２３（実施例）は、いずれも打ち抜き性が良好であり、表示ムラも少ないことがわかる。 As shown in Table 5, it can be seen that the polarizing plates 301 to 303, 310 to 312 and 315 to 323 (Examples) all have good punching properties and little display unevenness.
　特に、保護フィルムＢの引張弾性率を、保護フィルムＡの引張弾性率よりも高くすることで、打ち抜き性がより高まり、表示ムラをより抑制できることがわかる（偏光板３２０と３２２または３１７との対比）。これは、保護フィルムＢが適度な硬さを有することで、刃の押し込みに対する変形が少なく、それによって生じる応力も少なくできるためと考えられる。 In particular, it can be seen that by making the tensile elastic modulus of the protective film B higher than the tensile elastic modulus of the protective film A, the punching property is further enhanced and display unevenness can be further suppressed (comparison between the polarizing plate 320 and 322 or 317). ). It is considered that this is because the protective film B has an appropriate hardness, so that the deformation due to the pushing of the blade is small and the stress generated by the deformation can be reduced.
　また、保護フィルムＢの厚みを、保護フィルムＡの厚みよりも薄くすることで、打ち抜き性がより高まり、表示ムラをより抑制できることがわかる（偏光板３０１と３２３との対比）。これは、保護フィルムＢが適度に薄いことで、刃を抜く際、刃が引っかかりにくくなることで、クラックが抑制されやすく；かつ保護フィルムＢを薄くすることで、刃を押し込んだ時の物理的な変形（ひずみ）が少なくなり、生じる応力が小さくなったためと考えられる。 Further, it can be seen that by making the thickness of the protective film B thinner than the thickness of the protective film A, the punching property is further enhanced and the display unevenness can be further suppressed (comparison between the polarizing plates 301 and 323). This is because the protective film B is moderately thin, which makes it difficult for the blade to get caught when the blade is pulled out, which makes it easier to suppress cracks; and the thin protective film B makes it physically when the blade is pushed in. It is considered that this is because the deformation (strain) is reduced and the stress generated is reduced.
　これに対して、偏光板３０５～３０９および３１３～３１４（比較例）は、いずれも打ち抜き性が悪く、表示ムラも生じることがわかる。また、偏光板３０４（比較例）は、表示ムラを生じることがわかる。具体的には、偏光板３０５は、保護フィルムＢ中のゴム粒子ｂの平均アスペクト比が低いことから、応力を十分に緩和できなかったためと考えられる。偏光板３０４の表示ムラが悪いのは、保護フィルムＢ中のゴム粒子ｂの平均アスペクト比が高いことから、残留応力も高く、ゴム粒子ｂの塑性変形と、（メタ）アクリル系樹脂の塑性変形とでズレが生じ、ゴム粒子ｂと（メタ）アクリル系樹脂との間で界面剥離を生じやすくなり、その結果、保護フィルムＢと接着剤層との間の層間剥離を生じたためと考えられる。偏光板３０７は、保護フィルムＢがゴム粒子ｂを含まないため、脆すぎて、打ち抜き時の変形に耐えられず、クラックや欠けが生じたと考えられる。 On the other hand, it can be seen that the polarizing plates 305 to 309 and 313 to 314 (comparative examples) all have poor punching properties and display unevenness. Further, it can be seen that the polarizing plate 304 (comparative example) causes display unevenness. Specifically, it is considered that the polarizing plate 305 could not sufficiently relieve the stress because the average aspect ratio of the rubber particles b in the protective film B was low. The reason why the display unevenness of the polarizing plate 304 is poor is that the average aspect ratio of the rubber particles b in the protective film B is high, so that the residual stress is also high, and the plastic deformation of the rubber particles b and the plastic deformation of the (meth) acrylic resin It is probable that the rubber particles b and the (meth) acrylic resin are easily separated from each other, and as a result, the delamination between the protective film B and the adhesive layer is caused. Since the protective film B does not contain the rubber particles b, the polarizing plate 307 is considered to be too brittle to withstand deformation during punching, resulting in cracks and chips.
　また、偏光板３０８は、保護フィルムＡがゴム粒子ａを含まないため、打ち抜き時に、保護フィルムＡにクラックが生じやすくなったと考えられる。偏光板３０６において、打ち抜き性や表示ムラが低いのは、保護フィルムＡ中のゴム粒子ａの平均アスペクト比が高すぎるため、ゴム粒子ａが保護フィルムＡの変形に追従しやすくなり、保護フィルムＢに加わる応力が増えたためと考えられる。偏光板３１３および３１４において、打ち抜き性や表示ムラが低いのは、保護フィルムＢのＰＭＩの比率が多すぎて、フィルムの脆性が高くなり、ゴム粒子ｂに過剰な負荷がかかりやすくなり、樹脂にも負荷がかかりやすくなったためと考えられる。 Further, in the polarizing plate 308, since the protective film A does not contain the rubber particles a, it is considered that the protective film A is likely to be cracked at the time of punching. In the polarizing plate 306, the punching property and display unevenness are low because the average aspect ratio of the rubber particles a in the protective film A is too high, so that the rubber particles a easily follow the deformation of the protective film A, and the protective film B It is probable that the stress applied to the film increased. In the polarizing plates 313 and 314, the punching property and display unevenness are low because the ratio of PMI of the protective film B is too large, the brittleness of the film becomes high, the rubber particles b are easily overloaded, and the resin It is probable that the load was easily applied.
　また、偏光板３０９は、偏光板３０６よりも表示ムラがさらに低いことがわかる。これは、偏光板３０９に用いた保護フィルムＢに含まれる（メタ）アクリル系樹脂が、フェニルマレイミドに由来する構造単位を含まないため、ゴム粒子ｂと（メタ）アクリル系樹脂との間で界面剥離を生じたためと考えられる。 Further, it can be seen that the polarizing plate 309 has lower display unevenness than the polarizing plate 306. This is because the (meth) acrylic resin contained in the protective film B used for the polarizing plate 309 does not contain a structural unit derived from phenylmaleimide, so that the interface between the rubber particles b and the (meth) acrylic resin It is probable that the peeling occurred.
　本発明によれば、打ち抜き時のクラックや層間剥離を抑制でき、高湿環境下での長時間使用した際の打鍵による表示ムラを低減できる偏光板を提供することができる。 According to the present invention, it is possible to provide a polarizing plate capable of suppressing cracks and delamination during punching and reducing display unevenness due to keystrokes when used for a long time in a high humidity environment.
　１００　偏光板
　１１０　偏光子
　１２０Ａ　保護フィルム（保護フィルムＡ）
　１２０Ｂ　保護フィルム（保護フィルムＢ）
　１３０Ａ、１３０Ｂ　接着剤層
　１４０　粘着剤層
　１５０ａ　ゴム粒子（ゴム粒子ａ）
　１５０ｂ　ゴム粒子（ゴム粒子ｂ） 100 Polarizing plate 110 Polarizer 120A Protective film (Protective film A)
120B protective film (protective film B)
130A, 130B Adhesive layer 140 Adhesive layer 150a Rubber particles (rubber particles a)
150b rubber particles (rubber particles b)

Claims (7)

  1. 　偏光子と、前記偏光子の一方の面に配置された保護フィルムＡと、前記偏光子の他方の面に配置された保護フィルムＢと、前記保護フィルムＢの前記偏光子とは反対側の面に配置された粘着剤層とを含む偏光板であって、
    　前記保護フィルムＡは、（メタ）アクリル系樹脂と、ゴム粒子ａとを含み、
    　前記保護フィルムＢは、（メタ）アクリル系樹脂と、ゴム粒子ｂとを含み、
    　前記保護フィルムＡの厚み方向に沿った断面において、前記ゴム粒子ａの平均アスペクト比は、１．０～１．１であり、
    　前記保護フィルムＢの厚み方向に沿った断面において、前記ゴム粒子ｂの平均アスペクト比は、１．２～３．０であり、
    　前記保護フィルムＢに含まれる前記（メタ）アクリル系樹脂は、前記（メタ）アクリル系樹脂を構成する全構造単位に対して、５０～９５質量％のメタクリル酸メチルに由来する構造単位と、１～２５質量％のフェニルマレイミドに由来する構造単位と、１～２５質量％のアクリル酸アルキルエステルに由来する構造単位とを含む共重合体である、
    　偏光板。     The polarizer, the protective film A arranged on one surface of the polarizer, the protective film B arranged on the other surface of the polarizer, and the surface of the protective film B opposite to the polarizer. A polarizing plate including a pressure-sensitive adhesive layer arranged in
    The protective film A contains a (meth) acrylic resin and rubber particles a.
    The protective film B contains a (meth) acrylic resin and rubber particles b.
    In the cross section of the protective film A along the thickness direction, the average aspect ratio of the rubber particles a is 1.0 to 1.1.
    In the cross section of the protective film B along the thickness direction, the average aspect ratio of the rubber particles b is 1.2 to 3.0.
    The (meth) acrylic resin contained in the protective film B includes a structural unit derived from methyl methacrylate in an amount of 50 to 95% by mass based on all the structural units constituting the (meth) acrylic resin, and 1 A copolymer containing up to 25% by mass of a structural unit derived from phenylmaleimide and 1 to 25% by mass of a structural unit derived from an acrylic acid alkyl ester.
    Polarizer.
  2. 　前記保護フィルムＢの２５℃における引張弾性率は、前記保護フィルムＡの２５℃における引張弾性率よりも高い、
    　請求項１に記載の偏光板。     The tensile elastic modulus of the protective film B at 25 ° C. is higher than the tensile elastic modulus of the protective film A at 25 ° C.
    The polarizing plate according to claim 1.
  3. 　前記保護フィルムＡの２５℃における引張弾性率は、１．６～２．６ＧＰａであり、
    　前記保護フィルムＢの２５℃における引張弾性率は、２．４～３．４ＧＰａである、
    　請求項２に記載の偏光板。     The tensile elastic modulus of the protective film A at 25 ° C. is 1.6 to 2.6 GPa.
    The tensile elastic modulus of the protective film B at 25 ° C. is 2.4 to 3.4 GPa.
    The polarizing plate according to claim 2.
  4. 　前記保護フィルムＢにおける前記ゴム粒子ｂの含有量は、前記保護フィルムＡにおける前記ゴム粒子ａの含有量よりも少ない、
    　請求項２または３に記載の偏光板。     The content of the rubber particles b in the protective film B is smaller than the content of the rubber particles a in the protective film A.
    The polarizing plate according to claim 2 or 3.
  5. 　前記ゴム粒子ａは、スチレン類に由来する構造単位を含むアクリル系ゴム状重合体（ａ１）を含み、
    　前記ゴム粒子ｂは、スチレン類に由来する構造単位を含むアクリル系ゴム状重合体（ｂ１）を含み、
    　前記アクリル系ゴム条重合体（ｂ１）のスチレン類に由来する構造単位の含有量は、前記アクリル系ゴム状重合体（ａ１）のスチレン類に由来する構造単位の含有量よりも多い、
    　請求項１～４のいずれか一項に記載の偏光板。     The rubber particles a contain an acrylic rubber-like polymer (a1) containing a structural unit derived from styrenes.
    The rubber particles b contain an acrylic rubber-like polymer (b1) containing a structural unit derived from styrenes.
    The content of the structural unit derived from the styrenes of the acrylic rubber strip polymer (b1) is higher than the content of the structural unit derived from the styrenes of the acrylic rubber-like polymer (a1).
    The polarizing plate according to any one of claims 1 to 4.
  6. 　前記保護フィルムＢの厚みは、前記保護フィルムＡの厚みよりも薄い、
    　請求項１～５のいずれか一項に記載の偏光板。     The thickness of the protective film B is thinner than the thickness of the protective film A.
    The polarizing plate according to any one of claims 1 to 5.
  7. 　前記保護フィルムＡは、ポリメチルメタクリレートである、
    　請求項１～６のいずれか一項に記載の偏光板。     The protective film A is polymethylmethacrylate.
    The polarizing plate according to any one of claims 1 to 6.
PCT/JP2019/018115 2019-04-26 2019-04-26 Polarizing plate WO2020217511A1 (en)

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PCT/JP2019/018115 WO2020217511A1 (en) 2019-04-26 2019-04-26 Polarizing plate
JP2021515735A JP7367756B2 (en) 2019-04-26 2019-04-26 Polarizer
TW109108725A TWI733376B (en) 2019-04-26 2020-03-17 Polarizing plate

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CN116218393B (en) * 2022-12-30 2024-04-26 苏州赛伍应用技术股份有限公司 High-resistant Wen Fangsuan protective film and preparation method thereof

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JP2006259623A (en) * 2005-03-18 2006-09-28 Sekisui Chem Co Ltd Optical film, retardation film, polarizer protective film and polarizing plate
WO2006118168A1 (en) * 2005-04-28 2006-11-09 Konica Minolta Opto, Inc. Optical film, polarizing plate and liquid crystal display
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JP2006259623A (en) * 2005-03-18 2006-09-28 Sekisui Chem Co Ltd Optical film, retardation film, polarizer protective film and polarizing plate
WO2006118168A1 (en) * 2005-04-28 2006-11-09 Konica Minolta Opto, Inc. Optical film, polarizing plate and liquid crystal display
JP2008268417A (en) * 2007-04-18 2008-11-06 Konica Minolta Opto Inc Anisotropic scattering element, polarizing plate and liquid crystal display device
KR20180079490A (en) * 2016-12-30 2018-07-11 주식회사 효성 Ips lcd pannel

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CN116218393A (en) * 2022-12-30 2023-06-06 苏州赛伍应用技术股份有限公司 High Wen Fangsuan-resistant protective film and preparation method thereof
CN116218393B (en) * 2022-12-30 2024-04-26 苏州赛伍应用技术股份有限公司 High-resistant Wen Fangsuan protective film and preparation method thereof

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JPWO2020217511A1 (en) 2020-10-29
JP7367756B2 (en) 2023-10-24

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