WO2020054135A1 - Surface protection film base material, surface protection film using surface protection film base material, and optical film having surface protection film - Google Patents

Surface protection film base material, surface protection film using surface protection film base material, and optical film having surface protection film Download PDF

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Publication number
WO2020054135A1
WO2020054135A1 PCT/JP2019/020711 JP2019020711W WO2020054135A1 WO 2020054135 A1 WO2020054135 A1 WO 2020054135A1 JP 2019020711 W JP2019020711 W JP 2019020711W WO 2020054135 A1 WO2020054135 A1 WO 2020054135A1
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WO
WIPO (PCT)
Prior art keywords
surface protective
protective film
substrate
film
surface protection
Prior art date
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PCT/JP2019/020711
Other languages
French (fr)
Japanese (ja)
Inventor
清水　享
歩夢 中原
Original Assignee
日東電工株式会社
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Publication date
Application filed by 日東電工株式会社 filed Critical 日東電工株式会社
Priority to CN201980059578.5A priority Critical patent/CN112673292A/en
Priority to JP2020546689A priority patent/JPWO2020054135A1/en
Priority to KR1020217002234A priority patent/KR102604387B1/en
Publication of WO2020054135A1 publication Critical patent/WO2020054135A1/en

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Classifications

    • 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
    • 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
    • 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
    • B32B7/04—Interconnection of layers
    • B32B7/06—Interconnection of layers permitting easy separation
    • 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
    • B32B7/04—Interconnection of layers
    • B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18—Manufacture of films or sheets
    • 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
    • C09J7/22—Plastics; Metallised plastics
    • 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
    • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
    • C09J7/38—Pressure-sensitive adhesives [PSA]
    • 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
    • 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
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3083—Birefringent or phase retarding elements

Definitions

  • the present invention relates to a substrate for a surface protective film, a surface protective film using the substrate, and an optical film with a surface protective film.
  • An optical film for example, a polarizing plate or a laminate including a polarizing plate
  • An optical film includes the optical film (finally, the image display device) until the image display device to which the optical film is applied is actually used.
  • a surface protection film is releasably attached.
  • an optical display / surface protective film laminate is bonded to a display cell to produce an image display device, and the image display device is subjected to an optical test (for example, a lighting test) in a state where the laminate is bonded. ), And at an appropriate time thereafter, the surface protective film is peeled off.
  • the surface protective film typically has a resin film as a substrate and an adhesive layer.
  • the present invention has been made in order to solve the above conventional problems, and a main object of the present invention is to provide a surface protection film base material capable of favorably suppressing light leakage during optical inspection, coloring and rainbow unevenness. It is in.
  • the phase difference R0 (550) in the front direction and the phase difference R45 (550) in the polar angle of 45 ° and the azimuth angle of 45 ° satisfy the following relationship: R45 (550) -R0 (550) ⁇ 13 (nm).
  • the base material for a surface protective film has a front-side retardation R0 (550) of 20 nm or less.
  • the substrate for a surface protective film has a total light transmittance of 80% or more and a haze of 1.0% or less.
  • the substrate for a surface protection film contains at least one resin selected from polycarbonate, polyester, cycloolefin-based resin, acrylic resin, and cellulose resin. In one embodiment, the substrate for a surface protection film contains a resin having an alicyclic structure or an aromatic ring structure exhibiting negative intrinsic birefringence.
  • a surface protective film is provided. This surface protection film includes the above-mentioned substrate for a surface protection film and an adhesive layer.
  • an optical film with a surface protection film includes an optical film and the above-mentioned surface protective film releasably bonded to the optical film.
  • the optical inspection is performed by setting the difference between the phase difference R0 (550) in the front direction and the phase difference R45 (550) in the polar angle 45 ° and the azimuth angle 45 ° direction to a predetermined value or less. It is possible to realize a substrate for a surface protective film that can effectively suppress light leakage, coloring and rainbow unevenness at the time. In particular, in an optical inspection of a large-sized image display device, light leakage at an end can be significantly suppressed.
  • the substrate for surface protective film according to the embodiment of the present invention has a phase difference R0 (550) in the front direction and a phase difference R45 (550) in the polar angle of 45 ° and the azimuth angle of 45 ° as follows. Satisfy the relationship: R45 (550) -R0 (550) ⁇ 13 (nm). [R45 (550) -R0 (550)] is preferably at most 10 nm, more preferably at most 5 nm, further preferably at most 3 nm, particularly preferably at most 1 nm.
  • [R45 (550) -R0 (550)] is preferably -5 nm or more, more preferably -3 nm or more, and still more preferably -1 nm or more.
  • [R45 (550) -R0 (550)] is in such a range, a substrate for a surface protective film capable of favorably suppressing light leakage, coloring and rainbow unevenness during an optical inspection can be realized, In particular, in an optical inspection of a large-sized image display device, light leakage at an end can be significantly suppressed.
  • an image is taken by a camera (for example, a camera equipped with a polarizing filter) for each image display device while the image display device in which the optical film / surface protection film laminate is bonded to the display cell is transported in a roll.
  • a lighting defect of the image display device is inspected.
  • the angle of view of the camera becomes very large.
  • the angle of view in the long side direction of the image display device is 45 ° or more in one embodiment, 60 ° or more in another embodiment, and 70 ° or more in another embodiment. In another embodiment, it may be 82 ° or more.
  • the size of the image display device to which the substrate for a surface protection film (substantially, the surface protection film including the substrate) according to the embodiment of the present invention is applied is preferably 25 inches or more, more preferably 35 inches or more. Inches or more, more preferably 40 inches or more.
  • the higher the definition of the image display device the more noticeable the improvement of the inspection accuracy.
  • R0 ( ⁇ ) is a front-side phase difference measured with light having a wavelength of ⁇ nm at 23 ° C.
  • nx is the refractive index in the direction in which the in-plane refractive index is maximized (ie, the slow axis direction)
  • ny is the direction perpendicular to the slow axis in the plane (ie, fast phase). (Axial direction).
  • R45 ( ⁇ ) is a phase difference in a direction of a polar angle of 45 ° and an azimuth angle of 45 ° measured with light having a wavelength of ⁇ nm at 23 ° C.
  • the azimuth is a direction when the long side direction of the image display device is 0 °.
  • References to angles herein include both clockwise and counterclockwise directions with respect to a reference direction.
  • the front-side retardation R0 (550) of the surface protective film substrate is preferably 20 nm or less, more preferably 15 nm or less, further preferably 10 nm or less, and particularly preferably 5 nm or less.
  • the phase difference R0 (550) in the front direction is preferably as small as possible, and the lower limit is ideally 0 nm, for example, 0.3 nm.
  • Such a front-side phase difference R0 (550) can be realized by appropriately combining and setting the material forming the base material and the stretching conditions.
  • the phase difference R45 (550) in the polar angle 45 ° and the azimuth angle 45 ° direction of the surface protective film substrate is preferably 30 nm or less, more preferably 20 nm or less, further more preferably 12 nm or less, particularly Preferably it is 7 nm or less.
  • R45 (550) is in such a range, the desired [R45 (550) -R0 (550)] can be easily realized, and as a result, in the optical inspection of a large-sized image display device, the light at the end portion can be obtained. Leakage can be significantly suppressed. Similar to R0 (550), such R45 (550) can be realized by appropriately combining and setting the material forming the base material and the stretching conditions.
  • the thickness direction retardation Rth (550) of the surface protective film substrate is preferably -90 nm to +90 nm, more preferably -50 nm to +50 nm, and still more preferably -20 nm to +20 nm.
  • Rth ( ⁇ ) is a retardation in the thickness direction measured with light having a wavelength of ⁇ nm at 23 ° C.
  • nz is the refractive index in the thickness direction.
  • the substrate for a surface protective film may exhibit an inverse dispersion wavelength characteristic in which an in-plane retardation (a retardation in the front direction) increases according to the wavelength of the measurement light, and the in-plane retardation corresponds to the wavelength of the measurement light. It may show a positive wavelength dispersion characteristic that becomes smaller as a result, or may show a flat wavelength dispersion characteristic in which the in-plane phase difference hardly changes depending on the wavelength of the measurement light.
  • the total light transmittance of the substrate for a surface protective film is preferably 80% or more, more preferably 85% or more, further preferably 90% or more, and particularly preferably 95% or more.
  • the haze of the surface protective film substrate is preferably 1.0% or less, more preferably 0.7% or less, further preferably 0.5% or less, and particularly preferably 0.3% or less. % Or less. If the total light transmittance or haze is within such a range, when the surface protective film using the substrate for a surface protective film of the present invention is subjected to optical inspection of an image display device, excellent visibility is ensured. be able to. As a result, the accuracy of the optical inspection of the image display device can be significantly improved.
  • the base material for a surface protective film has a number of bending times to break in an MIT test of preferably 500 or more, more preferably 700 or more, still more preferably 900 or more, and particularly preferably 1100 or more. is there. That is, the substrate for a surface protective film can preferably have excellent flexibility or bending resistance. With such a configuration, it is possible to obtain a surface protective film which is excellent in operability at the time of laminating and peeling and in which cracking is suppressed. According to the embodiment of the present invention, it is possible to achieve both such excellent flexibility or bending resistance and the extremely small front-side phase difference R0 (550) as described above.
  • the MIT test can be performed in accordance with JIS P # 8115.
  • the substrate for a surface protective film has a water absorption of preferably 5% or less, more preferably 4% or less, and further preferably 2% or less.
  • the substrate for a surface protective film has a moisture permeability of preferably not more than 400 g / m 2 ⁇ 24 h, more preferably 160 g / m 2 ⁇ after being left for 24 hours in an environment of 40 ° C. and 92% RH. and at 24h or less, still more preferably not more than 130 g / m 2 ⁇ 24h, most preferably not more than 90g / m 2 ⁇ 24h. If the water absorption or the moisture permeability is in such a range, it is possible to suppress floating in a humid environment.
  • a water absorption can be measured based on JISK7209.
  • the water vapor transmission rate can be measured according to JIS Z 0208 (temperature and humidity conditions: 40 ° C., 90% RH).
  • the substrate for a surface protective film has a glass transition temperature (Tg) of preferably 145 ° C or higher, more preferably 160 ° C or higher.
  • Tg glass transition temperature
  • the pressure-sensitive adhesive layer can be formed by directly applying the pressure-sensitive adhesive layer to the surface protective film base when producing the surface protective film. In other words, there is no need to transfer the pressure-sensitive adhesive layer formed on the predetermined film to the substrate for the surface protection film. Therefore, a surface protection film can be produced with extremely excellent production efficiency.
  • the upper limit of the Tg of the substrate for a surface protective film may be, for example, 200 ° C.
  • the elastic modulus of the surface protective film substrate is preferably 50 MPa to 350 MPa at a tensile speed of 100 mm / min.
  • a surface protective film having excellent transportability and operability can be obtained.
  • the modulus of elasticity is measured according to JIS K7127: 1999.
  • the tensile elongation of the substrate for a surface protective film is preferably 70% to 200%.
  • the tensile elongation is measured according to JIS @ K # 6781.
  • the substrate for a surface protective film can be made of any appropriate material as long as it has the desired properties as described above.
  • the substrate for a surface protection film can be typically composed of a resin film.
  • the resin constituting the film include polyarylate, polyamide, polyimide, polyester, polyaryletherketone, polyamideimide, polyesterimide, polyvinyl alcohol, polyfumarate, polyethersulfone, polysulfone, and cycloolefin-based resins (for example, , A norbornene-based resin), polycarbonate, polyester carbonate, a cellulose resin (eg, triacetyl cellulose), an acrylic resin, and a polyurethane. These resins may be used alone or in combination.
  • the resin may have an alicyclic structure or an aromatic ring structure exhibiting negative intrinsic birefringence.
  • the alicyclic structure include a lactone ring structure, a glutaric anhydride structure, a glutarimide structure, an N-substituted maleimide structure, and a maleic anhydride structure.
  • the aromatic ring structure exhibiting negative intrinsic birefringence include a fluorene structure, a naphthalene structure, an anthracene structure, a carbazole structure, and a phthalimide structure. Resins having these structures have a small birefringence in the resulting film and can suppress a phase difference when formed into a film.
  • the substrate for the surface protective film may be, for example, a film using a film formed from the above resin as it is.
  • a method of forming a film from a resin any appropriate molding method can be adopted. Specific examples include a compression molding method, a transfer molding method, an injection molding method, an extrusion molding method, a blow molding method, a powder molding method, an FRP molding method, a cast coating method (for example, a casting method), a calendar molding method, and a hot press. And the like. Extrusion molding or cast coating is preferred. This is because the smoothness of the obtained film can be improved and good optical uniformity can be obtained.
  • the molding conditions can be set as appropriate according to the composition and type of the resin used, the characteristics desired for the substrate for the surface protective film, and the like.
  • the base material for a surface protective film may be a film obtained by subjecting a film formed from the above resin to a stretching treatment.
  • the stretching method of the film is typically biaxial stretching, and more specifically, sequential biaxial stretching or simultaneous biaxial stretching. This is because a substrate for a surface protective film having a small front-side retardation R0 (550) can be obtained.
  • the sequential biaxial stretching or simultaneous biaxial stretching is typically performed using a tenter stretching machine. Therefore, the stretching direction of the film is typically the length direction and the width direction of the film.
  • the stretching temperature can be changed according to R0 (550), R45 (550) and thickness desired for the surface protective film substrate, the type of resin used, the thickness of the film used, the stretching ratio, and the like.
  • the stretching temperature is preferably Tg + 5 ° C. to Tg + 50 ° C., more preferably Tg + 10 ° C. to Tg + 40 ° C., with respect to the glass transition temperature (Tg) of the film.
  • the stretching ratio can be changed according to R0 (550) and R45 (550) and the thickness desired for the surface protective film substrate, the type of resin used, the thickness of the film used, the stretching temperature, and the like.
  • biaxial stretching for example, sequential biaxial stretching or simultaneous biaxial stretching
  • stretching ratio in the first direction for example, length direction
  • stretching in the second direction for example, width direction
  • the magnification is preferably as small as possible, more preferably substantially equal.
  • the stretching ratio is determined in the first direction (for example, the length direction) and the second direction (for example, the width direction). For each, it can be, for example, from 1.1 times to 3.0 times.
  • the stretching speed is preferably 10% / sec or less, more preferably 7% / sec or less, further preferably 5% / sec or less, and particularly preferably 2.5% / sec or less.
  • the lower limit of the stretching speed can be, for example, 1.2% / sec. If the stretching speed is too low, the productivity may not be practical.
  • biaxial stretching for example, sequential biaxial stretching or simultaneous biaxial stretching
  • the stretching speed in the first direction (for example, the length direction) and the second direction (for example, the width direction) Is preferably as small as possible, and more preferably substantially equal. With such a configuration, R0 (550) and R45 (550) can be further reduced.
  • the substrate for a surface protective film may be a commercially available resin film as it is, or may be formed by subjecting a commercially available resin film to the above-described stretching treatment.
  • the thickness of the substrate for a surface protection film is typically from 10 ⁇ m to 100 ⁇ m, preferably from 20 ⁇ m to 70 ⁇ m.
  • the substrate for a surface protective film may have a slow axis.
  • the slow axis direction of the surface protection film substrate is relative to the long side direction of the image display device. It is preferably at most 30 °, more preferably at most 15 °, even more preferably at most 5 °, particularly preferably at most 2 °.
  • the slow axis is manifested when the front-side phase difference substantially exists. When the front-side phase difference approaches zero and substantially does not exist, the influence of the slow axis is small. Become.
  • the substrate for a surface protective film described in the above section A can be suitably used for a surface protective film. Therefore, embodiments of the present invention also include a surface protection film.
  • the surface protective film according to the embodiment of the present invention includes the surface protective film substrate described in the above section A and an adhesive layer.
  • any suitable pressure-sensitive adhesive can be adopted as the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer.
  • the base resin of the pressure-sensitive adhesive include an acrylic resin, a styrene resin, a silicone resin, a urethane resin, and a rubber resin. Such a base resin is described in, for example, JP-A-2015-120337 or JP-A-2011-201983. The descriptions in these publications are incorporated herein by reference. Acrylic resins are preferred from the viewpoints of chemical resistance, adhesion for preventing the intrusion of the treatment liquid during immersion, and the degree of freedom for the adherend.
  • the crosslinking agent that can be included in the pressure-sensitive adhesive include an isocyanate compound, an epoxy compound, and an aziridine compound.
  • the pressure-sensitive adhesive may include, for example, a silane coupling agent. The formulation of the pressure-sensitive adhesive can be appropriately set according to the purpose and desired properties.
  • the storage elastic modulus of the pressure-sensitive adhesive layer is preferably from 1.0 ⁇ 10 4 Pa to 1.0 ⁇ 10 7 Pa, and more preferably from 2.0 ⁇ 10 4 Pa to 5.0 ⁇ 10 6 Pa.
  • the storage elastic modulus can be determined, for example, from dynamic viscoelasticity measurement at a temperature of 23 ° C. and an angular velocity of 0.1 rad / s.
  • the thickness of the pressure-sensitive adhesive layer is preferably 1 ⁇ m to 60 ⁇ m, more preferably 3 ⁇ m to 30 ⁇ m. If the thickness is too small, the adhesiveness becomes insufficient, and air bubbles and the like may enter the adhesive interface. If the thickness is too large, problems such as sticking out of the pressure-sensitive adhesive tend to occur.
  • the separator is temporarily attached to the surface of the pressure-sensitive adhesive layer in a releasable manner until the surface protective film is actually used (that is, the surface protective film is bonded to an optical film or an image display device).
  • the separator include a plastic (eg, polyethylene terephthalate (PET), polyethylene, polypropylene) film, nonwoven fabric, or the like, which is surface-coated with a release agent such as a silicone release agent, a fluorine release agent, or a long-chain alkyl acrylate release agent. Paper and the like. Any appropriate thickness can be adopted for the thickness of the separator depending on the purpose.
  • the thickness of the separator is, for example, 10 ⁇ m to 100 ⁇ m.
  • the embodiment of the present invention also includes an optical film with a surface protection film.
  • An optical film with a surface protective film according to an embodiment of the present invention includes an optical film and the surface protective film according to the above item B, which is releasably attached to the optical film.
  • the optical film may be a single film or a laminate.
  • Specific examples of the optical film include a polarizer, a retardation film, a polarizing plate (typically, a laminate of a polarizer and a protective film), a conductive film for a touch panel, a surface-treated film, and for these purposes.
  • a laminate for example, an anti-reflection circular polarizer, a polarizer with a conductive layer for a touch panel, a polarizer with a retardation layer, and a prism sheet-integrated polarizer
  • appropriately laminated according to the requirements is given.
  • the angle between the absorption axis direction of the polarizer and the slow axis direction of the surface protective film substrate is preferably 0 ° ⁇ 30 ° or 90 ° ⁇ 30 °, Preferably it is 0 ° ⁇ 15 ° or 90 ° ⁇ 15 °, more preferably 0 ° ⁇ 5 ° or 90 ° ⁇ 5 °.
  • the angle is in such a range, light leakage, coloring, and rainbow unevenness during an optical inspection can be satisfactorily suppressed. Particularly, in an optical inspection of a large-sized image display device, light leakage at an end portion is remarkable. Can be suppressed.
  • R0 (550), thickness direction retardation Rth (550) and R45 (550) The base material for a surface protective film obtained in each of the examples and comparative examples was cut into a length of 4 cm and a width of 4 cm to obtain a measurement sample.
  • R0 (550), thickness direction retardation Rth (550), and R45 (550) of the measurement sample were measured using a product name "Axoscan" manufactured by Axometrics.
  • the measurement wavelength was 550 nm, and the measurement temperature was 23 ° C.
  • Nijimura The surface protective film substrates obtained in the examples and comparative examples were arranged between two polarizing plates in a crossed Nicols state.
  • the surface protection film substrate was disposed such that the length direction of the surface protection film substrate was parallel to the transmission axis direction of one of the polarizing plates.
  • light from a fluorescent lamp was irradiated from below the lower polarizing plate, and the presence or absence of rainbow unevenness was visually observed.
  • Evaluation was made according to the following criteria. :: No rainbow unevenness was observed. ⁇ : Slight rainbow unevenness was observed. X: Rainbow unevenness was significantly observed. (3) Brightness Commercially available liquid crystal television (manufactured by LG, 49 inches, product name “49SJ8000”)
  • the base material for a surface protective film obtained in each of Examples and Comparative Examples was bonded to the viewing-side polarizing plate of (2) via an adhesive.
  • the surface protective films including the substrate for a surface protective film obtained in Examples and Comparative Examples were bonded.
  • the entire input image was displayed in white and turned on.
  • the brightness of the lit liquid crystal television was measured using a product name “SR-UL2” manufactured by Topcon Technohouse Co., Ltd.
  • “REGQ1298DUHC3” manufactured by Nitto Denko Corporation was attached to the lens portion of SL-UL2 in an axial arrangement so as to be crossed with the viewing side polarizing plate, and the luminance was measured.
  • the directions of measurement were a total of three places: a front direction, a 45 ° azimuth azimuth 45 ° direction, and a 45 ° azimuth 135 ° azimuth direction.
  • Example 1 After vacuum drying a commercially available polycarbonate resin film (manufactured by Mitsubishi Chemical Corporation, trade name “DURABIO T7450A”) at 105 ° C. for 5 hours, a single screw extruder (manufactured by Toshiba Machine Co., cylinder temperature 230 ° C.), a T-die (width) A film having a thickness of 40 ⁇ m was prepared using a film forming apparatus equipped with a cast roll (temperature: 1700 mm, temperature: 230 ° C.), a cast roll (temperature: 120 ° C.) and a winder, and used as a substrate for a surface protective film. This film exhibited flat wavelength dispersion characteristics.
  • R0 (550) of the obtained base material for surface protective film was 5.6 nm
  • Rth (550) was 11.5 nm
  • R45 (550) was 6.02 nm
  • [R45 (550) -R0 (550)] was 0.42 nm.
  • the obtained substrate for a surface protective film was subjected to the above-mentioned evaluations (2) to (4). Table 1 shows the results.
  • Example 2 A substrate for a surface protective film (thickness: 15 ⁇ m) was obtained in the same manner as in Example 1 except that the extrusion amount of the extruder and the speed of the cast roll were adjusted.
  • R0 (550) of the obtained base material for surface protective film was 11.2 nm
  • Rth (550) was 17.8 nm
  • R45 (550) was 11.9 nm
  • [R45 (550) -R0 (550)] was 0.7 nm.
  • the obtained substrate for a surface protective film was subjected to the above-mentioned evaluations (2) to (4). Table 1 shows the results.
  • Example 3 Commercially available polycarbonate resin (trade name “Iupilon H-4000” manufactured by Mitsubishi Engineering-Plastics Corporation) was vacuum-dried at 120 ° C. for 5 hours, and then a single-screw extruder (manufactured by Toshiba Machine Co., cylinder temperature 255 ° C.), T Using a film forming apparatus equipped with a die (width 1700 mm, temperature 255 ° C.), cast roll (temperature 130 ° C.) and a winder, a film having a thickness of 40 ⁇ m was prepared and used as a substrate for a surface protective film.
  • a single-screw extruder manufactured by Toshiba Machine Co., cylinder temperature 255 ° C.
  • T Using a film forming apparatus equipped with a die (width 1700 mm, temperature 255 ° C.), cast roll (temperature 130 ° C.) and a winder, a film having a thickness of 40 ⁇ m was prepared and used as a substrate for
  • R0 (550) of the obtained base material for surface protective film was 2.6 nm
  • Rth (550) was 43.9 nm
  • R45 (550) was 15.1 nm
  • [R45 (550) ⁇ R0 ( 550)] was 12.5 nm
  • the obtained substrate for a surface protective film was subjected to the evaluations of the above (2) to (4), and the results are shown in Table 1.
  • Example 4 A polymer alloy film was prepared using the following raw materials.
  • R0 (550) of the obtained base material for surface protective film was 20 nm
  • Rth (550) was 85 nm
  • R45 (550) was 28.1 nm
  • [R45 (550) -R0 (550)]. was 8.1 nm.
  • the obtained substrate for a surface protective film was subjected to the above-mentioned evaluations (2) to (4). Table 1 shows the results.
  • Example 5 A commercially available triacetyl cellulose (TAC) film (manufactured by FUJIFILM Corporation, product name "TD80UL”) was used as it was to prepare a substrate for a surface protection film (thickness: 80 m).
  • R0 (550) of the substrate for a surface protective film is 4.9 nm
  • Rth (550) is 52.6 nm
  • R45 (550) is 8.7 nm
  • [R45 (550) -R0 (550). ] was 3.8 nm.
  • the substrate for a surface protective film was subjected to the evaluations (2) to (4) above. Table 1 shows the results.
  • Example 6 A substrate for a surface protection film (thickness: 40 ⁇ m) was obtained in the same manner as in Example 1 except that a commercially available cycloolefin-based resin film (manufactured by Zeon Corporation, product name “ZF14”) was used.
  • R0 (550) of the obtained base material for surface protective film was 2.0 nm
  • Rth (550) was 7.9 nm
  • R45 (550) was 2.7 nm
  • [R45 (550) -R0 (550)] was 0.7 nm.
  • the obtained substrate for a surface protective film was subjected to the above-mentioned evaluations (2) to (4). Table 1 shows the results.
  • Example 7 After vacuum drying a commercially available acrylic resin (trade name “CM-205”, manufactured by Kimei Industry Co., Ltd.) at 100 ° C. for 5 hours, a single screw extruder (manufactured by Toshiba Machine Co., cylinder temperature 230 ° C.), T-die (width) A film having a thickness of 160 ⁇ m was produced using a film forming apparatus equipped with a cast roll (temperature 1100 mm, temperature 230 ° C.), a cast roll (temperature 100 ° C.) and a winder. This film was simultaneously biaxially stretched twice in the length and width directions. The stretching temperature was 146 ° C., and the stretching speed was 7.1% / sec in both the length and width directions.
  • CM-205 commercially available acrylic resin
  • a single screw extruder manufactured by Toshiba Machine Co., cylinder temperature 230 ° C.
  • T-die width
  • a film having a thickness of 160 ⁇ m was produced using a film forming apparatus equipped with a cast roll
  • a substrate for a surface protective film (thickness: 40 ⁇ m) was obtained.
  • R0 (550) of the obtained substrate for surface protective film was 0.5 nm
  • Rth (550) was ⁇ 39 nm
  • R45 (550) was 10.1 nm
  • [R45 (550) ⁇ R0 ( 550)] was 9.6 nm.
  • the obtained substrate for a surface protective film was subjected to the above-mentioned evaluations (2) to (4). Table 1 shows the results.
  • a substrate for a surface protective film (40 ⁇ m in thickness) was obtained in the same manner as in Example 4 except that the stretching temperature was 167 ° C.
  • R0 (550) of the obtained base material for surface protective film is 32 nm
  • Rth (550) is 91 nm
  • R45 (550) is 45.1 nm
  • [R45 (550) -R0 (550)] was 13.1 nm.
  • the obtained substrate for a surface protective film was subjected to the above-mentioned evaluations (2) to (4). Table 1 shows the results.
  • a substrate for a surface protection film (thickness: 80 ⁇ m) was obtained in the same manner as in Example 3 except that the thickness was changed to 80 ⁇ m.
  • R0 (550) of the obtained base material for surface protective film is 5.6 nm
  • Rth (550) is 102.6 nm
  • R45 (550) is 19.4 nm
  • [R45 (550) -R0 (550)] was 13.8 nm.
  • the obtained substrate for a surface protective film was subjected to the above-mentioned evaluations (2) to (4). Table 1 shows the results.
  • ⁇ Comparative Example 3> A commercially available ultra-high retardation polyethylene terephthalate film (trade name “Diafoil MRF38CK” manufactured by Mitsubishi Chemical Corporation) was used as it was to prepare a substrate for a surface protection film (thickness: 38 ⁇ m).
  • R0 (550) of the substrate for surface protective film is 2950 nm
  • Rth (550) is 8899.4 nm
  • R45 (550) is 3445.5 nm
  • [R45 (550) -R0 (550)] is It was 495.5 nm.
  • the substrate for a surface protective film was subjected to the evaluations (2) to (4) above. Table 1 shows the results.
  • the substrate for a surface protective film of the example of the present invention prevents rainbow unevenness, has excellent total light transmittance, and suppresses light leakage at the end. . In addition, it was confirmed that the same result as that of rainbow unevenness and light leakage was obtained for coloring.
  • the substrate for a surface protective film of the present invention is suitably used for a surface protective film.
  • the surface protective film of the present invention is used to protect the optical film until the optical film (finally, the image display device) is actually used.

Abstract

Provided is a surface protection film base material that can favorably suppress light leakage, staining, and iridescent irregularity during optical inspections. The phase difference R0(550) of this surface protection film base material in the frontal direction and the phase difference R45(550) of the surface protection film base material in a 45°polar angle and a 45° azimuth angle direction satisfy the following expression: R45(550)- R0(550)≤13 (nm). In one embodiment, the phase difference R0(550) of the surface protection film base material in the frontal direction is 20 nm or lower.

Description

表面保護フィルム用基材、該基材を用いた表面保護フィルム、および表面保護フィルム付光学フィルムSubstrate for surface protective film, surface protective film using the substrate, and optical film with surface protective film
　本発明は、表面保護フィルム用基材、該基材を用いた表面保護フィルム、および表面保護フィルム付光学フィルムに関する。 The present invention relates to a substrate for a surface protective film, a surface protective film using the substrate, and an optical film with a surface protective film.
　光学フィルム（例えば、偏光板、偏光板を含む積層体）には、当該光学フィルムが適用される画像表示装置が実際に使用されるまでの間、当該光学フィルム（最終的には、画像表示装置）を保護するために表面保護フィルムが剥離可能に貼り合わせられている。実用的には、光学フィルム／表面保護フィルムの積層体が表示セルに貼り合わせられて画像表示装置が作製され、当該積層体が貼り合わせられた状態で画像表示装置が光学試験（例えば、点灯試験）に供され、その後の適切な時点で表面保護フィルムが剥離除去される。表面保護フィルムは、代表的には、基材としての樹脂フィルムと粘着剤層とを有する。従来の表面保護フィルムによれば、光学検査の際に光漏れ、着色、虹ムラ等が発生し、光学検査の精度低下の原因となる場合がある。その結果、画像表示装置自体には問題がないにもかかわらず出荷前の光学検査で不良と判断されてしまう場合があり、これにより、画像表示装置の製造から出荷までの効率が低下してしまうという問題がある。 An optical film (for example, a polarizing plate or a laminate including a polarizing plate) includes the optical film (finally, the image display device) until the image display device to which the optical film is applied is actually used. In order to protect the surface protection film, a surface protection film is releasably attached. Practically, an optical display / surface protective film laminate is bonded to a display cell to produce an image display device, and the image display device is subjected to an optical test (for example, a lighting test) in a state where the laminate is bonded. ), And at an appropriate time thereafter, the surface protective film is peeled off. The surface protective film typically has a resin film as a substrate and an adhesive layer. According to the conventional surface protection film, light leakage, coloring, rainbow unevenness, and the like occur during an optical inspection, which may cause a decrease in the accuracy of the optical inspection. As a result, there is a case where the image display device itself is determined to be defective by an optical inspection before shipment even though there is no problem in the image display device itself, thereby lowering the efficiency from manufacture to shipment of the image display device. There is a problem.
特開２０１７－１９０４０６号公報JP 2017-190406 A
　本発明は上記従来の課題を解決するためになされたものであり、その主たる目的は、光学検査時の光漏れ、着色および虹ムラを良好に抑制し得る表面保護フィルム用基材を提供することにある。 The present invention has been made in order to solve the above conventional problems, and a main object of the present invention is to provide a surface protection film base material capable of favorably suppressing light leakage during optical inspection, coloring and rainbow unevenness. It is in.
　本発明の実施形態による表面保護フィルム用基材は、正面方向の位相差Ｒ０（５５０）と極角４５°および方位角４５°方向の位相差Ｒ４５（５５０）とが下記の関係を満足する：
　　　Ｒ４５（５５０）－Ｒ０（５５０）≦１３（ｎｍ）。
　１つの実施形態においては、上記表面保護フィルム用基材は、上記正面方向の位相差Ｒ０（５５０）が２０ｎｍ以下である。
　１つの実施形態においては、上記表面保護フィルム用基材は、全光線透過率が８０％以上であり、ヘイズが１．０％以下である。
　１つの実施形態においては、上記表面保護フィルム用基材は、ポリカーボネート、ポリエステル、シクロオレフィン系樹脂、アクリル系樹脂およびセルロース樹脂から選択される少なくとも1つの樹脂を含む。１つの実施形態においては、上記表面保護フィルム用基材は、脂環式構造または負の固有複屈折を示す芳香族環構造を有する樹脂を含む。
　本発明の別の局面によれば、表面保護フィルムが提供される。この表面保護フィルムは、上記表面保護フィルム用基材と粘着剤層とを含む。
　本発明のさらに別の局面によれば、表面保護フィルム付光学フィルムが提供される。この表面保護フィルム付光学フィルムは、光学フィルムと、該光学フィルムに剥離可能に貼り合わせられた上記表面保護フィルムと、を含む。 In the substrate for a surface protection film according to the embodiment of the present invention, the phase difference R0 (550) in the front direction and the phase difference R45 (550) in the polar angle of 45 ° and the azimuth angle of 45 ° satisfy the following relationship:
R45 (550) -R0 (550) ≤13 (nm).
In one embodiment, the base material for a surface protective film has a front-side retardation R0 (550) of 20 nm or less.
In one embodiment, the substrate for a surface protective film has a total light transmittance of 80% or more and a haze of 1.0% or less.
In one embodiment, the substrate for a surface protection film contains at least one resin selected from polycarbonate, polyester, cycloolefin-based resin, acrylic resin, and cellulose resin. In one embodiment, the substrate for a surface protection film contains a resin having an alicyclic structure or an aromatic ring structure exhibiting negative intrinsic birefringence.
According to another aspect of the present invention, a surface protective film is provided. This surface protection film includes the above-mentioned substrate for a surface protection film and an adhesive layer.
According to still another aspect of the present invention, there is provided an optical film with a surface protection film. This optical film with a surface protective film includes an optical film and the above-mentioned surface protective film releasably bonded to the optical film.
　本発明の実施形態によれば、正面方向の位相差Ｒ０（５５０）と極角４５°および方位角４５°方向の位相差Ｒ４５（５５０）との差を所定値以下とすることにより、光学検査時の光漏れ、着色および虹ムラを良好に抑制し得る表面保護フィルム用基材を実現することができる。特に、大型の画像表示装置の光学検査において、端部の光漏れを顕著に抑制することができる。 According to the embodiment of the present invention, the optical inspection is performed by setting the difference between the phase difference R0 (550) in the front direction and the phase difference R45 (550) in the polar angle 45 ° and the azimuth angle 45 ° direction to a predetermined value or less. It is possible to realize a substrate for a surface protective film that can effectively suppress light leakage, coloring and rainbow unevenness at the time. In particular, in an optical inspection of a large-sized image display device, light leakage at an end can be significantly suppressed.
　以下、本発明の好ましい実施形態について説明するが、本発明はこれらの実施形態には限定されない。 Hereinafter, preferred embodiments of the present invention will be described, but the present invention is not limited to these embodiments.
Ａ．表面保護フィルム用基材
　本発明の実施形態による表面保護フィルム用基材は、正面方向の位相差Ｒ０（５５０）と極角４５°および方位角４５°方向の位相差Ｒ４５（５５０）とが下記の関係を満足する：
　　　Ｒ４５（５５０）－Ｒ０（５５０）≦１３（ｎｍ）。
　［Ｒ４５（５５０）－Ｒ０（５５０）］は、好ましくは１０ｎｍ以下であり、より好ましくは５ｎｍ以下であり、さらに好ましくは３ｎｍ以下であり、特に好ましくは１ｎｍ以下である。一方、［Ｒ４５（５５０）－Ｒ０（５５０）］は、好ましくは－５ｎｍ以上であり、より好ましくは－３ｎｍ以上であり、さらに好ましくは－１ｎｍ以上である。［Ｒ４５（５５０）－Ｒ０（５５０）］の絶対値は、小さければ小さいほど好ましい。［Ｒ４５（５５０）－Ｒ０（５５０）］がこのような範囲であれば、光学検査時の光漏れ、着色および虹ムラを良好に抑制し得る表面保護フィルム用基材を実現することができ、特に、大型の画像表示装置の光学検査において、端部の光漏れを顕著に抑制することができる。例えば、光学検査は、光学フィルム／表面保護フィルムの積層体が表示セルに貼り合わせられた画像表示装置をロール搬送しながら画像表示装置ごとにカメラ（例えば、偏光フィルターを取り付けたカメラ）で撮影することにより、画像表示装置の点灯欠点等を検査する。ここで、画像表示装置が大型である場合には、カメラの画角が非常に大きくなる。画像表示装置の長辺方向の画角は、１つの実施形態においては４５°以上であり、別の実施形態においては６０°以上であり、さらに別の実施形態においては７０°以上であり、さらに別の実施形態においては８２°以上であり得る。本発明の実施形態によれば、このように画角が非常に大きい場合であっても端部（または周縁部）の光漏れを顕著に抑制することができる。本発明の実施形態による表面保護フィルム用基材（実質的には、当該基材を含む表面保護フィルム）が適用される画像表示装置のサイズは、好ましくは２５インチ以上であり、より好ましくは３５インチ以上であり、さらに好ましくは４０インチ以上である。画像表示装置が大型であるほど、本発明の効果（特に、端部の光漏れ防止）が顕著となる。さらに、本発明の実施形態によれば、画像表示装置が高精細であるほど、検査精度の向上が顕著となる。なお、本明細書において「Ｒ０（λ）」は、２３℃における波長λｎｍの光で測定した正面方向の位相差である。Ｒ０（λ）は、層（フィルム）の厚みをｄ（ｎｍ）としたとき、式：Ｒｅ＝（ｎｘ－ｎｙ）×ｄによって求められる。したがって、「Ｒ０（５５０）」は、２３℃における波長５５０ｎｍの光で測定した正面方向の位相差である。ここで、「ｎｘ」は面内の屈折率が最大になる方向（すなわち、遅相軸方向）の屈折率であり、「ｎｙ」は面内で遅相軸と直交する方向（すなわち、進相軸方向）の屈折率である。また、「Ｒ４５（λ）」は、２３℃における波長λｎｍの光で測定した極角４５°および方位角４５°方向の位相差である。ここで、方位角は画像表示装置の長辺方向を０°としたときの方向である。本明細書において角度に言及するときは、基準方向に対して時計回りおよび反時計回りの両方の方向を包含する。 A. Substrate for Surface Protective Film The substrate for surface protective film according to the embodiment of the present invention has a phase difference R0 (550) in the front direction and a phase difference R45 (550) in the polar angle of 45 ° and the azimuth angle of 45 ° as follows. Satisfy the relationship:
R45 (550) -R0 (550) ≤13 (nm).
[R45 (550) -R0 (550)] is preferably at most 10 nm, more preferably at most 5 nm, further preferably at most 3 nm, particularly preferably at most 1 nm. On the other hand, [R45 (550) -R0 (550)] is preferably -5 nm or more, more preferably -3 nm or more, and still more preferably -1 nm or more. The smaller the absolute value of [R45 (550) -R0 (550)], the better. When [R45 (550) -R0 (550)] is in such a range, a substrate for a surface protective film capable of favorably suppressing light leakage, coloring and rainbow unevenness during an optical inspection can be realized, In particular, in an optical inspection of a large-sized image display device, light leakage at an end can be significantly suppressed. For example, in the optical inspection, an image is taken by a camera (for example, a camera equipped with a polarizing filter) for each image display device while the image display device in which the optical film / surface protection film laminate is bonded to the display cell is transported in a roll. Thus, a lighting defect of the image display device is inspected. Here, when the image display device is large, the angle of view of the camera becomes very large. The angle of view in the long side direction of the image display device is 45 ° or more in one embodiment, 60 ° or more in another embodiment, and 70 ° or more in another embodiment. In another embodiment, it may be 82 ° or more. According to the embodiment of the present invention, even when the angle of view is very large, light leakage at an end (or a peripheral edge) can be significantly suppressed. The size of the image display device to which the substrate for a surface protection film (substantially, the surface protection film including the substrate) according to the embodiment of the present invention is applied is preferably 25 inches or more, more preferably 35 inches or more. Inches or more, more preferably 40 inches or more. The larger the image display device is, the more remarkable the effect of the present invention (especially, prevention of light leakage at the end portion). Furthermore, according to the embodiment of the present invention, the higher the definition of the image display device, the more noticeable the improvement of the inspection accuracy. In the present specification, “R0 (λ)” is a front-side phase difference measured with light having a wavelength of λ nm at 23 ° C. R0 (λ) is determined by the formula: Re = (nx−ny) × d, where d (nm) is the thickness of the layer (film). Therefore, “R0 (550)” is the phase difference in the front direction measured with light having a wavelength of 550 nm at 23 ° C. Here, “nx” is the refractive index in the direction in which the in-plane refractive index is maximized (ie, the slow axis direction), and “ny” is the direction perpendicular to the slow axis in the plane (ie, fast phase). (Axial direction). “R45 (λ)” is a phase difference in a direction of a polar angle of 45 ° and an azimuth angle of 45 ° measured with light having a wavelength of λ nm at 23 ° C. Here, the azimuth is a direction when the long side direction of the image display device is 0 °. References to angles herein include both clockwise and counterclockwise directions with respect to a reference direction.
　表面保護フィルム用基材の正面方向の位相差Ｒ０（５５０）は、好ましくは２０ｎｍ以下であり、より好ましくは１５ｎｍ以下であり、さらに好ましくは１０ｎｍ以下であり、特に好ましくは５ｎｍ以下である。正面方向の位相差Ｒ０（５５０）は小さいほど好ましく、その下限は理想的には０ｎｍであり、例えば０．３ｎｍであり得る。Ｒ０（５５０）がこのような範囲であれば、本発明の表面保護フィルム用基材を用いた表面保護フィルムを画像表示装置の光学検査に供した場合に、光漏れ、着色および虹ムラを良好に抑制することができる。その結果、画像表示装置の光学検査の精度を顕著に向上させることができ、画像表示装置の製造から出荷までの効率を向上させることができる。このような正面方向の位相差Ｒ０（５５０）は、基材を構成する材料と延伸条件とを適切に組み合わせて設定することにより実現され得る。 (4) The front-side retardation R0 (550) of the surface protective film substrate is preferably 20 nm or less, more preferably 15 nm or less, further preferably 10 nm or less, and particularly preferably 5 nm or less. The phase difference R0 (550) in the front direction is preferably as small as possible, and the lower limit is ideally 0 nm, for example, 0.3 nm. When R0 (550) is within such a range, when the surface protective film using the substrate for a surface protective film of the present invention is subjected to an optical inspection of an image display device, good light leakage, coloring, and uneven rainbow are obtained. Can be suppressed. As a result, the accuracy of the optical inspection of the image display device can be remarkably improved, and the efficiency of the image display device from manufacture to shipment can be improved. Such a front-side phase difference R0 (550) can be realized by appropriately combining and setting the material forming the base material and the stretching conditions.
　表面保護フィルム用基材の極角４５°および方位角４５°方向の位相差Ｒ４５（５５０）は、好ましくは３０ｎｍ以下であり、より好ましくは２０ｎｍ以下であり、さらに好ましくは１２ｎｍ以下であり、特に好ましくは７ｎｍ以下である。Ｒ４５（５５０）がこのような範囲であれば、上記所望の［Ｒ４５（５５０）－Ｒ０（５５０）］が実現しやすくなり、その結果、大型の画像表示装置の光学検査において、端部の光漏れを顕著に抑制することができる。このようなＲ４５（５５０）は、Ｒ０（５５０）と同様に、基材を構成する材料と延伸条件とを適切に組み合わせて設定することにより実現され得る。 The phase difference R45 (550) in the polar angle 45 ° and the azimuth angle 45 ° direction of the surface protective film substrate is preferably 30 nm or less, more preferably 20 nm or less, further more preferably 12 nm or less, particularly Preferably it is 7 nm or less. When R45 (550) is in such a range, the desired [R45 (550) -R0 (550)] can be easily realized, and as a result, in the optical inspection of a large-sized image display device, the light at the end portion can be obtained. Leakage can be significantly suppressed. Similar to R0 (550), such R45 (550) can be realized by appropriately combining and setting the material forming the base material and the stretching conditions.
　表面保護フィルム用基材の厚み方向位相差Ｒｔｈ（５５０）は、好ましくは－９０ｎｍ～＋９０ｎｍであり、より好ましくは－５０ｎｍ～＋５０ｎｍであり、さらに好ましくは－２０ｎｍ～＋２０ｎｍである。「Ｒｔｈ（λ）」は、２３℃における波長λｎｍの光で測定した厚み方向の位相差である。Ｒｔｈ（λ）は、層（フィルム）の厚みをｄ（ｎｍ）としたとき、式：Ｒｔｈ＝（ｎｘ－ｎｚ）×ｄによって求められる。したがって、「Ｒｔｈ（５５０）」は、２３℃における波長５５０ｎｍの光で測定した厚み方向の位相差である。ここで、「ｎｚ」は厚み方向の屈折率である。 厚 み The thickness direction retardation Rth (550) of the surface protective film substrate is preferably -90 nm to +90 nm, more preferably -50 nm to +50 nm, and still more preferably -20 nm to +20 nm. “Rth (λ)” is a retardation in the thickness direction measured with light having a wavelength of λ nm at 23 ° C. Rth (λ) is determined by the formula: Rth = (nx−nz) × d, where d (nm) is the thickness of the layer (film). Therefore, “Rth (550)” is a retardation in the thickness direction measured with light having a wavelength of 550 nm at 23 ° C. Here, “nz” is the refractive index in the thickness direction.
　表面保護フィルム用基材は、面内位相差（正面方向の位相差）が測定光の波長に応じて大きくなる逆分散波長特性を示してもよく、面内位相差が測定光の波長に応じて小さくなる正の波長分散特性を示してもよく、面内位相差が測定光の波長によってもほとんど変化しないフラットな波長分散特性を示してもよい。 The substrate for a surface protective film may exhibit an inverse dispersion wavelength characteristic in which an in-plane retardation (a retardation in the front direction) increases according to the wavelength of the measurement light, and the in-plane retardation corresponds to the wavelength of the measurement light. It may show a positive wavelength dispersion characteristic that becomes smaller as a result, or may show a flat wavelength dispersion characteristic in which the in-plane phase difference hardly changes depending on the wavelength of the measurement light.
　表面保護フィルム用基材の全光線透過率は、好ましくは８０％以上であり、より好ましくは８５％以上であり、さらに好ましくは９０％以上であり、特に好ましくは９５％以上である。さらに、表面保護フィルム用基材のヘイズは、好ましくは１．０％以下であり、より好ましくは０．７％以下であり、さらに好ましくは０．５％以下であり、特に好ましくは０．３％以下である。全光線透過率またはヘイズがこのような範囲であれば、本発明の表面保護フィルム用基材を用いた表面保護フィルムを画像表示装置の光学検査に供した場合に、優れた視認性を確保することができる。その結果、画像表示装置の光学検査の精度を顕著に向上させることができる。 全 The total light transmittance of the substrate for a surface protective film is preferably 80% or more, more preferably 85% or more, further preferably 90% or more, and particularly preferably 95% or more. Further, the haze of the surface protective film substrate is preferably 1.0% or less, more preferably 0.7% or less, further preferably 0.5% or less, and particularly preferably 0.3% or less. % Or less. If the total light transmittance or haze is within such a range, when the surface protective film using the substrate for a surface protective film of the present invention is subjected to optical inspection of an image display device, excellent visibility is ensured. be able to. As a result, the accuracy of the optical inspection of the image display device can be significantly improved.
　表面保護フィルム用基材は、ＭＩＴ試験における破断までの折り曲げ回数が好ましくは５００回以上であり、より好ましくは７００回以上であり、さらに好ましくは９００回以上であり、特に好ましくは１１００回以上である。すなわち、表面保護フィルム用基材は、好ましくは優れた可撓性または耐折り曲げ性を有し得る。このような構成であれば、貼り合わせ時および剥離時の操作性に優れ、かつ、割れが抑制された表面保護フィルムを得ることができる。本発明の実施形態によれば、このような優れた可撓性または耐折り曲げ性と上記のような非常に小さい正面方向の位相差Ｒ０（５５０）とを両立することができる。なお、ＭＩＴ試験は、ＪＩＳ　Ｐ　８１１５に準拠して行われ得る。 The base material for a surface protective film has a number of bending times to break in an MIT test of preferably 500 or more, more preferably 700 or more, still more preferably 900 or more, and particularly preferably 1100 or more. is there. That is, the substrate for a surface protective film can preferably have excellent flexibility or bending resistance. With such a configuration, it is possible to obtain a surface protective film which is excellent in operability at the time of laminating and peeling and in which cracking is suppressed. According to the embodiment of the present invention, it is possible to achieve both such excellent flexibility or bending resistance and the extremely small front-side phase difference R0 (550) as described above. The MIT test can be performed in accordance with JIS P # 8115.
　表面保護フィルム用基材は、吸水率が好ましくは５％以下であり、より好ましくは４％以下であり、さらに好ましくは２％以下である。また、表面保護フィルム用基材は、４０℃および９２％ＲＨの環境下に２４時間放置した後の透湿度が、好ましくは４００ｇ／ｍ２・２４ｈ以下であり、より好ましくは１６０ｇ／ｍ２・２４ｈ以下であり、さらに好ましくは１３０ｇ／ｍ２・２４ｈ以下であり、特に好ましくは９０ｇ／ｍ２・２４ｈ以下である。吸水率または透湿度がこのような範囲であれば、加湿環境下における浮きを抑制することができる。その結果、長距離輸送（例えば、輸出）時の品質安定性が確保され得る。なお、吸水率は、ＪＩＳ　Ｋ　７２０９に準拠して測定され得る。透湿度は、ＪＩＳ　Ｚ　０２０８に準拠して測定され得る（温湿度条件：４０℃、９０％ＲＨ）。 The substrate for a surface protective film has a water absorption of preferably 5% or less, more preferably 4% or less, and further preferably 2% or less. In addition, the substrate for a surface protective film has a moisture permeability of preferably not more than 400 g / m 2 · 24 h, more preferably 160 g / m 2 ··· after being left for 24 hours in an environment of 40 ° C. and 92% RH. and at 24h or less, still more preferably not more than 130 g / m 2 · 24h, most preferably not more than 90g / m 2 · 24h. If the water absorption or the moisture permeability is in such a range, it is possible to suppress floating in a humid environment. As a result, quality stability during long-distance transportation (for example, export) can be ensured. In addition, a water absorption can be measured based on JISK7209. The water vapor transmission rate can be measured according to JIS Z 0208 (temperature and humidity conditions: 40 ° C., 90% RH).
　表面保護フィルム用基材は、ガラス転移温度（Ｔｇ）が好ましくは１４５℃以上であり、より好ましくは１６０℃以上である。Ｔｇがこのような範囲であれば、表面保護フィルムを作製する際に粘着剤層を表面保護フィルム用基材に直接塗工することにより形成することができる。言い換えれば、所定のフィルム上に形成した粘着剤層を表面保護フィルム用基材に転写する必要がない。したがって、非常に優れた製造効率で表面保護フィルムを作製することができる。一方、表面保護フィルム用基材のＴｇの上限は、例えば２００℃であり得る。 基材 The substrate for a surface protective film has a glass transition temperature (Tg) of preferably 145 ° C or higher, more preferably 160 ° C or higher. When the Tg is in such a range, the pressure-sensitive adhesive layer can be formed by directly applying the pressure-sensitive adhesive layer to the surface protective film base when producing the surface protective film. In other words, there is no need to transfer the pressure-sensitive adhesive layer formed on the predetermined film to the substrate for the surface protection film. Therefore, a surface protection film can be produced with extremely excellent production efficiency. On the other hand, the upper limit of the Tg of the substrate for a surface protective film may be, for example, 200 ° C.
　表面保護フィルム用基材の弾性率は、好ましくは、引張速度１００ｍｍ／ｍｉｎにおいて５０ＭＰａ～３５０ＭＰａである。弾性率がこのような範囲であれば、搬送性および操作性に優れた表面保護フィルムを得ることができる。本発明の実施形態によれば、優れた弾性率（強さ）と上記のような優れた可撓性または耐折り曲げ性（柔らかさ）とを両立することができる。なお、弾性率は、ＪＩＳ　Ｋ　７１２７：１９９９に準拠して測定される。 (4) The elastic modulus of the surface protective film substrate is preferably 50 MPa to 350 MPa at a tensile speed of 100 mm / min. When the elastic modulus is in such a range, a surface protective film having excellent transportability and operability can be obtained. According to the embodiment of the present invention, it is possible to achieve both excellent elastic modulus (strength) and excellent flexibility or bending resistance (softness) as described above. The modulus of elasticity is measured according to JIS K7127: 1999.
　表面保護フィルム用基材の引張伸度は、好ましくは７０％～２００％である。引張伸度がこのような範囲であれば、搬送中に破断しにくいという利点を有する。なお、引張伸度は、ＪＩＳ　Ｋ　６７８１に準拠して測定される。 引 張 The tensile elongation of the substrate for a surface protective film is preferably 70% to 200%. When the tensile elongation is in such a range, there is an advantage that it is difficult to break during transportation. The tensile elongation is measured according to JIS @ K # 6781.
　表面保護フィルム用基材は、上記のような所望の特性を有し得る限り、任意の適切な材料で構成され得る。表面保護フィルム用基材は、代表的には樹脂フィルムで構成され得る。フィルムを構成する樹脂としては、例えば、ポリアリレート、ポリアミド、ポリイミド、ポリエステル、ポリアリールエーテルケトン、ポリアミドイミド、ポリエステルイミド、ポリビニルアルコール、ポリフマル酸エステル、ポリエーテルサルフォン、ポリサルフォン、シクロオレフィン系樹脂（例えば、ノルボルネン系樹脂）、ポリカーボネート、ポリエステルカーボネート、セルロース樹脂（例えば、トリアセチルセルロース）、アクリル系樹脂およびポリウレタンが挙げられる。これらの樹脂は、単独で用いてもよく組み合わせて用いてもよい。１つの実施形態においては、上記の樹脂は、脂環式構造または負の固有複屈折を示す芳香族環構造を有していてもよい。脂環式構造としては、例えば、ラクトン環構造、無水グルタル酸構造、グルタルイミド構造、Ｎ－置換マレイミド構造、無水マレイン酸構造が挙げられる。負の固有複屈折を示す芳香族環構造としては、例えば、フルオレン構造、ナフタレン構造、アントラセン構造、カルバゾール構造、フタルイミド構造が挙げられる。これらの構造を有する樹脂は、得られるフィルムの複屈折が小さく、フィルム化した際の位相差を抑制することができる。 (4) The substrate for a surface protective film can be made of any appropriate material as long as it has the desired properties as described above. The substrate for a surface protection film can be typically composed of a resin film. Examples of the resin constituting the film include polyarylate, polyamide, polyimide, polyester, polyaryletherketone, polyamideimide, polyesterimide, polyvinyl alcohol, polyfumarate, polyethersulfone, polysulfone, and cycloolefin-based resins (for example, , A norbornene-based resin), polycarbonate, polyester carbonate, a cellulose resin (eg, triacetyl cellulose), an acrylic resin, and a polyurethane. These resins may be used alone or in combination. In one embodiment, the resin may have an alicyclic structure or an aromatic ring structure exhibiting negative intrinsic birefringence. Examples of the alicyclic structure include a lactone ring structure, a glutaric anhydride structure, a glutarimide structure, an N-substituted maleimide structure, and a maleic anhydride structure. Examples of the aromatic ring structure exhibiting negative intrinsic birefringence include a fluorene structure, a naphthalene structure, an anthracene structure, a carbazole structure, and a phthalimide structure. Resins having these structures have a small birefringence in the resulting film and can suppress a phase difference when formed into a film.
　表面保護フィルム用基材は、例えば、上記樹脂から形成されたフィルムをそのまま用いたフィルムであり得る。樹脂からフィルムを形成する方法としては、任意の適切な成形加工法が採用され得る。具体例としては、圧縮成形法、トランスファー成形法、射出成形法、押出成形法、ブロー成形法、粉末成形法、ＦＲＰ成形法、キャスト塗工法（例えば、流延法）、カレンダー成形法、熱プレス法等が挙げられる。押出成形法またはキャスト塗工法が好ましい。得られるフィルムの平滑性を高め、良好な光学的均一性を得ることができるからである。成形条件は、使用される樹脂の組成や種類、表面保護フィルム用基材に所望される特性等に応じて適宜設定され得る。 基材 The substrate for the surface protective film may be, for example, a film using a film formed from the above resin as it is. As a method of forming a film from a resin, any appropriate molding method can be adopted. Specific examples include a compression molding method, a transfer molding method, an injection molding method, an extrusion molding method, a blow molding method, a powder molding method, an FRP molding method, a cast coating method (for example, a casting method), a calendar molding method, and a hot press. And the like. Extrusion molding or cast coating is preferred. This is because the smoothness of the obtained film can be improved and good optical uniformity can be obtained. The molding conditions can be set as appropriate according to the composition and type of the resin used, the characteristics desired for the substrate for the surface protective film, and the like.
　また例えば、表面保護フィルム用基材は、上記樹脂から形成されたフィルムに延伸処理を施したフィルムであってもよい。フィルムの延伸方法は、代表的には二軸延伸であり、より詳細には逐次二軸延伸または同時二軸延伸である。正面方向の位相差Ｒ０（５５０）が小さい表面保護フィルム用基材が得られるからである。逐次二軸延伸または同時二軸延伸は、代表的にはテンター延伸機を用いて行われる。したがって、フィルムの延伸方向は、代表的にはフィルムの長さ方向および幅方向である。 For example, the base material for a surface protective film may be a film obtained by subjecting a film formed from the above resin to a stretching treatment. The stretching method of the film is typically biaxial stretching, and more specifically, sequential biaxial stretching or simultaneous biaxial stretching. This is because a substrate for a surface protective film having a small front-side retardation R0 (550) can be obtained. The sequential biaxial stretching or simultaneous biaxial stretching is typically performed using a tenter stretching machine. Therefore, the stretching direction of the film is typically the length direction and the width direction of the film.
　延伸温度は、表面保護フィルム用基材に所望されるＲ０（５５０）、Ｒ４５（５５０）および厚み、使用される樹脂の種類、使用されるフィルムの厚み、延伸倍率等に応じて変化し得る。具体的には、延伸温度は、フィルムのガラス転移温度（Ｔｇ）に対し、好ましくはＴｇ＋５℃～Ｔｇ＋５０℃であり、より好ましくはＴｇ＋１０℃～Ｔｇ＋４０℃である。このような温度で延伸することにより、本発明の実施形態において適切な特性を有する表面保護フィルム用基材が得られ得る。 The stretching temperature can be changed according to R0 (550), R45 (550) and thickness desired for the surface protective film substrate, the type of resin used, the thickness of the film used, the stretching ratio, and the like. Specifically, the stretching temperature is preferably Tg + 5 ° C. to Tg + 50 ° C., more preferably Tg + 10 ° C. to Tg + 40 ° C., with respect to the glass transition temperature (Tg) of the film. By stretching at such a temperature, a substrate for a surface protective film having appropriate characteristics in the embodiment of the present invention can be obtained.
　延伸倍率は、表面保護フィルム用基材に所望されるＲ０（５５０）、Ｒ４５（５５０）および厚み、使用される樹脂の種類、使用されるフィルムの厚み、延伸温度等に応じて変化し得る。二軸延伸（例えば、逐次二軸延伸または同時二軸延伸）を採用する場合には、第１の方向（例えば、長さ方向）の延伸倍率と第２の方向（例えば、幅方向）の延伸倍率とは、好ましくはその差ができる限り小さく、より好ましくは実質的に等しい。このような構成であれば、Ｒ０（５５０）、Ｒ４５（５５０）が小さい表面保護フィルム用基材が得られ得る。二軸延伸（例えば、逐次二軸延伸または同時二軸延伸）を採用する場合には、延伸倍率は、第１の方向（例えば、長さ方向）および第２の方向（例えば、幅方向）のそれぞれについて、例えば１．１倍～３．０倍であり得る。 The stretching ratio can be changed according to R0 (550) and R45 (550) and the thickness desired for the surface protective film substrate, the type of resin used, the thickness of the film used, the stretching temperature, and the like. When employing biaxial stretching (for example, sequential biaxial stretching or simultaneous biaxial stretching), stretching ratio in the first direction (for example, length direction) and stretching in the second direction (for example, width direction) The magnification is preferably as small as possible, more preferably substantially equal. With such a configuration, a substrate for a surface protective film having a small R0 (550) and R45 (550) can be obtained. When biaxial stretching (for example, sequential biaxial stretching or simultaneous biaxial stretching) is employed, the stretching ratio is determined in the first direction (for example, the length direction) and the second direction (for example, the width direction). For each, it can be, for example, from 1.1 times to 3.0 times.
　延伸速度は、好ましくは１０％／秒以下であり、より好ましくは７％／秒以下であり、さらに好ましくは５％／秒以下であり、特に好ましくは２．５％／秒以下である。このような小さい延伸速度で延伸することにより、Ｒ０（５５０）およびＲ４５（５５０）が小さい表面保護フィルム用基材が得られ得る。延伸速度の下限は、例えば１．２％／秒であり得る。延伸速度が小さすぎると、生産性が実用的でなくなる場合がある。なお、二軸延伸（例えば、逐次二軸延伸または同時二軸延伸）を採用する場合には、第１の方向（例えば、長さ方向）の延伸速度と第２の方向（例えば、幅方向）の延伸速度とは、好ましくはその差ができる限り小さく、より好ましくは実質的に等しい。このような構成であれば、Ｒ０（５５０）およびＲ４５（５５０）をより小さくすることができる。 The stretching speed is preferably 10% / sec or less, more preferably 7% / sec or less, further preferably 5% / sec or less, and particularly preferably 2.5% / sec or less. By stretching at such a low stretching speed, a substrate for a surface protective film having small R0 (550) and R45 (550) can be obtained. The lower limit of the stretching speed can be, for example, 1.2% / sec. If the stretching speed is too low, the productivity may not be practical. When biaxial stretching (for example, sequential biaxial stretching or simultaneous biaxial stretching) is employed, the stretching speed in the first direction (for example, the length direction) and the second direction (for example, the width direction) Is preferably as small as possible, and more preferably substantially equal. With such a configuration, R0 (550) and R45 (550) can be further reduced.
　表面保護フィルム用基材は、市販の樹脂フィルムをそのまま用いてもよく、市販の樹脂フィルムを上記のような延伸処理に供することにより形成されてもよい。 基材 The substrate for a surface protective film may be a commercially available resin film as it is, or may be formed by subjecting a commercially available resin film to the above-described stretching treatment.
　表面保護フィルム用基材の厚みは、代表的には１０μｍ～１００μｍであり、好ましくは２０μｍ～７０μｍである。 基材 The thickness of the substrate for a surface protection film is typically from 10 μm to 100 μm, preferably from 20 μm to 70 μm.
　表面保護フィルム用基材は、上記のとおり正面方向の位相差を有するので、遅相軸を有し得る。表面保護フィルム用基材（実質的には、表面保護フィルム）が画像表示装置に適用された場合、表面保護フィルム用基材の遅相軸方向は、画像表示装置の長辺方向に対して、好ましくは３０°以下であり、より好ましくは１５°以下であり、さらに好ましくは５°以下であり、特に好ましくは２°以下である。このような構成であれば、光学検査時の光漏れ、着色および虹ムラを良好に抑制することができ、特に、大型の画像表示装置の光学検査において、端部の光漏れを顕著に抑制することができる。なお、遅相軸は正面方向の位相差が実質的に存在する場合に発現するものであり、正面方向の位相差が０に近づき実質的に存在しない場合には、遅相軸の影響は小さくなる。 基材 Since the substrate for a surface protective film has a retardation in the front direction as described above, it may have a slow axis. When the surface protection film substrate (substantially, the surface protection film) is applied to the image display device, the slow axis direction of the surface protection film substrate is relative to the long side direction of the image display device. It is preferably at most 30 °, more preferably at most 15 °, even more preferably at most 5 °, particularly preferably at most 2 °. With such a configuration, light leakage, coloring, and rainbow unevenness during an optical inspection can be favorably suppressed, and particularly, in an optical inspection of a large-sized image display device, light leakage at an end portion is significantly suppressed. be able to. Note that the slow axis is manifested when the front-side phase difference substantially exists. When the front-side phase difference approaches zero and substantially does not exist, the influence of the slow axis is small. Become.
Ｂ．表面保護フィルム
　上記Ａ項に記載の表面保護フィルム用基材は、表面保護フィルムに好適に用いられ得る。したがって、本発明の実施形態は、表面保護フィルムも包含する。本発明の実施形態による表面保護フィルムは、上記Ａ項に記載の表面保護フィルム用基材と粘着剤層とを含む。 B. Surface protective film The substrate for a surface protective film described in the above section A can be suitably used for a surface protective film. Therefore, embodiments of the present invention also include a surface protection film. The surface protective film according to the embodiment of the present invention includes the surface protective film substrate described in the above section A and an adhesive layer.
　粘着剤層を形成する粘着剤としては、任意の適切な粘着剤が採用され得る。粘着剤のベース樹脂としては、例えば、アクリル系樹脂、スチレン系樹脂、シリコーン系樹脂、ウレタン系樹脂、ゴム系樹脂が挙げられる。このようなベース樹脂は、例えば、特開２０１５－１２０３３７号公報または特開２０１１－２０１９８３号公報に記載されている。これらの公報の記載は、本明細書に参考として援用される。耐薬品性、浸漬時における処理液の浸入を防止するための密着性、被着体への自由度等の観点から、アクリル系樹脂が好ましい。粘着剤に含まれ得る架橋剤としては、例えば、イソシアネート化合物、エポキシ化合物、アジリジン化合物が挙げられる。粘着剤は、例えばシランカップリング剤を含んでいてもよい。粘着剤の配合処方は、目的および所望の特性に応じて適切に設定され得る。 粘着 Any suitable pressure-sensitive adhesive can be adopted as the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer. Examples of the base resin of the pressure-sensitive adhesive include an acrylic resin, a styrene resin, a silicone resin, a urethane resin, and a rubber resin. Such a base resin is described in, for example, JP-A-2015-120337 or JP-A-2011-201983. The descriptions in these publications are incorporated herein by reference. Acrylic resins are preferred from the viewpoints of chemical resistance, adhesion for preventing the intrusion of the treatment liquid during immersion, and the degree of freedom for the adherend. Examples of the crosslinking agent that can be included in the pressure-sensitive adhesive include an isocyanate compound, an epoxy compound, and an aziridine compound. The pressure-sensitive adhesive may include, for example, a silane coupling agent. The formulation of the pressure-sensitive adhesive can be appropriately set according to the purpose and desired properties.
　粘着剤層の貯蔵弾性率は、好ましくは１．０×１０４Ｐａ～１．０×１０７Ｐａであり、より好ましくは２．０×１０４Ｐａ～５．０×１０６Ｐａである。粘着剤層の貯蔵弾性率がこのような範囲であれば、ロール形成時のブロッキングを抑制することができる。なお、貯蔵弾性率は、例えば、温度２３℃および角速度０．１ｒａｄ／ｓでの動的粘弾性測定から求めることができる。 The storage elastic modulus of the pressure-sensitive adhesive layer is preferably from 1.0 × 10 4 Pa to 1.0 × 10 7 Pa, and more preferably from 2.0 × 10 4 Pa to 5.0 × 10 6 Pa. When the storage elastic modulus of the pressure-sensitive adhesive layer is in such a range, blocking during roll formation can be suppressed. The storage elastic modulus can be determined, for example, from dynamic viscoelasticity measurement at a temperature of 23 ° C. and an angular velocity of 0.1 rad / s.
　粘着剤層の厚みは、好ましくは１μｍ～６０μｍであり、より好ましくは３μｍ～３０μｍである。厚みが薄すぎると、粘着性が不十分となり、粘着界面に気泡等が入り込む場合がある。厚みが厚すぎると、粘着剤がはみ出すなどの不具合が生じやすくなる。 The thickness of the pressure-sensitive adhesive layer is preferably 1 μm to 60 μm, more preferably 3 μm to 30 μm. If the thickness is too small, the adhesiveness becomes insufficient, and air bubbles and the like may enter the adhesive interface. If the thickness is too large, problems such as sticking out of the pressure-sensitive adhesive tend to occur.
　実用的には、表面保護フィルムが実際に使用される（すなわち、光学フィルムまたは画像表示装置に貼り合わせられる）までの間、粘着剤層表面にセパレーターが剥離可能に仮着されている。セパレーターを設けることにより、粘着剤層を保護するとともに、表面保護フィルムをロール状に巻き取ることが可能となる。セパレーターとしては、例えば、シリコーン系剥離剤、フッ素系剥離剤、長鎖アルキルアクリレート系剥離剤等の剥離剤により表面コートされたプラスチック（例えば、ポリエチレンテレフタレート（ＰＥＴ）、ポリエチレン、ポリプロピレン）フィルム、不織布または紙などが挙げられる。セパレーターの厚みは、目的に応じて任意の適切な厚みを採用することができる。セパレーターの厚みは、例えば１０μｍ～１００μｍである。 Practically, the separator is temporarily attached to the surface of the pressure-sensitive adhesive layer in a releasable manner until the surface protective film is actually used (that is, the surface protective film is bonded to an optical film or an image display device). By providing the separator, the pressure-sensitive adhesive layer can be protected, and the surface protection film can be wound into a roll. Examples of the separator include a plastic (eg, polyethylene terephthalate (PET), polyethylene, polypropylene) film, nonwoven fabric, or the like, which is surface-coated with a release agent such as a silicone release agent, a fluorine release agent, or a long-chain alkyl acrylate release agent. Paper and the like. Any appropriate thickness can be adopted for the thickness of the separator depending on the purpose. The thickness of the separator is, for example, 10 μm to 100 μm.
Ｃ．表面保護フィルム付光学フィルム
　上記Ｂ項に記載の表面保護フィルムは、光学フィルム（最終的には、画像表示装置）が実際に使用されるまでの間、当該光学フィルムを保護するために用いられる。したがって、本発明の実施形態は、表面保護フィルム付光学フィルムも包含する。本発明の実施形態による表面保護フィルム付光学フィルムは、光学フィルムと、当該光学フィルムに剥離可能に貼り合わせられた上記Ｂ項に記載の表面保護フィルムとを含む。 C. Optical Film with Surface Protective Film The surface protective film described in the above section B is used for protecting the optical film until the optical film (finally, the image display device) is actually used. Therefore, the embodiment of the present invention also includes an optical film with a surface protection film. An optical film with a surface protective film according to an embodiment of the present invention includes an optical film and the surface protective film according to the above item B, which is releasably attached to the optical film.
　光学フィルムは、単一フィルムであってもよく積層体であってもよい。光学フィルムの具体例としては、偏光子、位相差フィルム、偏光板（代表的には、偏光子と保護フィルムとの積層体）、タッチパネル用導電性フィルム、表面処理フィルム、ならびに、これらを目的に応じて適切に積層した積層体（例えば、反射防止用円偏光板、タッチパネル用導電層付偏光板、位相差層付偏光板、プリズムシート一体型偏光板）が挙げられる。 The optical film may be a single film or a laminate. Specific examples of the optical film include a polarizer, a retardation film, a polarizing plate (typically, a laminate of a polarizer and a protective film), a conductive film for a touch panel, a surface-treated film, and for these purposes. A laminate (for example, an anti-reflection circular polarizer, a polarizer with a conductive layer for a touch panel, a polarizer with a retardation layer, and a prism sheet-integrated polarizer) appropriately laminated according to the requirements is given.
　光学フィルムが偏光子を含む場合、偏光子の吸収軸方向と表面保護フィルム用基材の遅相軸方向とのなす角度は、好ましくは０°±３０°または９０°±３０°であり、より好ましくは０°±１５°または９０°±１５°であり、さらに好ましくは０°±５°または９０°±５°である。当該角度がこのような範囲であれば、光学検査時の光漏れ、着色および虹ムラを良好に抑制することができ、特に、大型の画像表示装置の光学検査において、端部の光漏れを顕著に抑制することができる。 When the optical film contains a polarizer, the angle between the absorption axis direction of the polarizer and the slow axis direction of the surface protective film substrate is preferably 0 ° ± 30 ° or 90 ° ± 30 °, Preferably it is 0 ° ± 15 ° or 90 ° ± 15 °, more preferably 0 ° ± 5 ° or 90 ° ± 5 °. When the angle is in such a range, light leakage, coloring, and rainbow unevenness during an optical inspection can be satisfactorily suppressed. Particularly, in an optical inspection of a large-sized image display device, light leakage at an end portion is remarkable. Can be suppressed.
　以下、実施例によって本発明を具体的に説明するが、本発明はこれら実施例によって限定されるものではない。実施例における各特性の測定方法は以下の通りである。なお、特に明記しない限り、実施例における「部」および「％」は重量基準である。 Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. The measuring method of each characteristic in the example is as follows. Unless otherwise specified, “parts” and “%” in Examples are on a weight basis.
（１）Ｒ０（５５０）、厚み方向位相差Ｒｔｈ（５５０）およびＲ４５（５５０）
　実施例および比較例で得られた表面保護フィルム用基材を長さ４ｃｍおよび幅４ｃｍに切り出し、測定試料とした。当該測定試料について、Ａｘｏｍｅｔｒｉｃｓ社製、製品名「Ａｘｏｓｃａｎ」を用いてＲ０（５５０）、厚み方向位相差Ｒｔｈ（５５０）およびＲ４５（５５０）を測定した。測定波長は５５０ｎｍ、測定温度は２３℃であった。
（２）虹ムラ
　実施例および比較例で得られた表面保護フィルム用基材を、クロスニコル状態の２枚の偏光板の間に配置した。その際、表面保護フィルム用基材の長さ方向と一方の偏光板の透過軸方向とが平行となるように表面保護フィルム用基材を配置した。その状態で下側偏光板の下側から蛍光灯の光を照射し、虹ムラの有無を目視により観察した。以下の基準で評価した。
　　　　　○：虹ムラは認められなかった
　　　　　△：虹ムラがわずかに認められた
　　　　　×：虹ムラが顕著に認められた
（３）輝度
　市販の液晶テレビ（ＬＧ社製、４９インチ、製品名「４９ＳＪ８０００」）の視認側偏光板の上に、実施例および比較例で得られた表面保護フィルム用基材を、粘着剤を介して貼り合わせた。すなわち、実施例および比較例で得られた表面保護フィルム用基材を含む表面保護フィルムを貼り合わせた。その状態で、入力画像を全面白表示させて点灯させた。点灯させた液晶テレビの輝度を株式会社トプコンテクノハウス製　製品名「ＳＲ－ＵＬ２」を用いて測定した。また、ＳＬ－ＵＬ２のレンズ部に視認側偏光板とクロスニコルになるような軸配置で日東電工社製「ＲＥＧＱ１２９８ＤＵＨＣ３」を貼り付け、輝度を測定した。測定の方向は、正面方向、極角４５°方位角４５°方向、および、極角４５°方位角１３５°方向の合計３か所であった。
（４）端部の光漏れ
　市販の液晶テレビ（ＬＧ社製、４９インチ、製品名「４９ＳＪ８０００」）の視認側偏光板の上に、実施例および比較例で得られた表面保護フィルム用基材を、粘着剤を介して貼り合わせた。すなわち、実施例および比較例で得られた表面保護フィルム用基材を含む表面保護フィルムを貼り合わせた。その状態で、入力画像を全面白表示させて点灯させた。点灯中の液晶テレビを偏光サングラス越しに観察し、端部の光漏れについて以下の基準で評価した。なお、サングラスに貼りわされている偏光板の吸収軸はメガネの上下方向であった。
　　　　　○：光漏れは認められなかった
　　　　　△：光漏れがわずかに認められた
　　　　　×：光漏れが顕著であった (1) R0 (550), thickness direction retardation Rth (550) and R45 (550)
The base material for a surface protective film obtained in each of the examples and comparative examples was cut into a length of 4 cm and a width of 4 cm to obtain a measurement sample. R0 (550), thickness direction retardation Rth (550), and R45 (550) of the measurement sample were measured using a product name "Axoscan" manufactured by Axometrics. The measurement wavelength was 550 nm, and the measurement temperature was 23 ° C.
(2) Nijimura The surface protective film substrates obtained in the examples and comparative examples were arranged between two polarizing plates in a crossed Nicols state. At that time, the surface protection film substrate was disposed such that the length direction of the surface protection film substrate was parallel to the transmission axis direction of one of the polarizing plates. In this state, light from a fluorescent lamp was irradiated from below the lower polarizing plate, and the presence or absence of rainbow unevenness was visually observed. Evaluation was made according to the following criteria.
：: No rainbow unevenness was observed. Δ: Slight rainbow unevenness was observed. X: Rainbow unevenness was significantly observed. (3) Brightness Commercially available liquid crystal television (manufactured by LG, 49 inches, product name “49SJ8000”) The base material for a surface protective film obtained in each of Examples and Comparative Examples was bonded to the viewing-side polarizing plate of (2) via an adhesive. That is, the surface protective films including the substrate for a surface protective film obtained in Examples and Comparative Examples were bonded. In this state, the entire input image was displayed in white and turned on. The brightness of the lit liquid crystal television was measured using a product name “SR-UL2” manufactured by Topcon Technohouse Co., Ltd. Further, “REGQ1298DUHC3” manufactured by Nitto Denko Corporation was attached to the lens portion of SL-UL2 in an axial arrangement so as to be crossed with the viewing side polarizing plate, and the luminance was measured. The directions of measurement were a total of three places: a front direction, a 45 ° azimuth azimuth 45 ° direction, and a 45 ° azimuth 135 ° azimuth direction.
(4) Light Leakage at the End A surface protective film substrate obtained in Examples and Comparative Examples was placed on a viewing side polarizing plate of a commercially available liquid crystal television (manufactured by LG, 49 inches, product name "49SJ8000"). Were bonded via an adhesive. That is, the surface protective films including the substrate for a surface protective film obtained in Examples and Comparative Examples were bonded. In this state, the entire input image was displayed in white and turned on. The lit liquid crystal television was observed through polarized sunglasses, and light leakage at the end was evaluated according to the following criteria. The absorption axis of the polarizing plate attached to the sunglasses was in the vertical direction of the glasses.
：: no light leakage was observed Δ: slight light leakage was observed ×: light leakage was remarkable
＜実施例１＞
　市販のポリカーボネート樹脂フィルム（三菱ケミカル社製、商品名「ＤＵＲＡＢＩＯ　Ｔ７４５０Ａ」）を１０５℃で５時間真空乾燥をした後、単軸押出機（東芝機械社製、シリンダー温度２３０℃）、Ｔダイ（幅１７００ｍｍ、温度２３０℃）、キャストロール（温度１２０℃）および巻取機を備えたフィルム製膜装置を用いて、厚み４０μｍのフィルムを作製し、表面保護フィルム用基材とした。このフィルムはフラットな波長分散特性を示した。得られた表面保護フィルム用基材のＲ０（５５０）は５．６ｎｍであり、Ｒｔｈ（５５０）は１１．５ｎｍであり、Ｒ４５（５５０）は６．０２ｎｍであり、［Ｒ４５（５５０）－Ｒ０（５５０）］は０．４２ｎｍであった。得られた表面保護フィルム用基材を上記（２）～（４）の評価に供した。結果を表１に示す。 <Example 1>
After vacuum drying a commercially available polycarbonate resin film (manufactured by Mitsubishi Chemical Corporation, trade name “DURABIO T7450A”) at 105 ° C. for 5 hours, a single screw extruder (manufactured by Toshiba Machine Co., cylinder temperature 230 ° C.), a T-die (width) A film having a thickness of 40 μm was prepared using a film forming apparatus equipped with a cast roll (temperature: 1700 mm, temperature: 230 ° C.), a cast roll (temperature: 120 ° C.) and a winder, and used as a substrate for a surface protective film. This film exhibited flat wavelength dispersion characteristics. R0 (550) of the obtained base material for surface protective film was 5.6 nm, Rth (550) was 11.5 nm, R45 (550) was 6.02 nm, and [R45 (550) -R0 (550)] was 0.42 nm. The obtained substrate for a surface protective film was subjected to the above-mentioned evaluations (2) to (4). Table 1 shows the results.
＜実施例２＞
　押出機の押出量およびキャストロールの速度を調整したこと以外は実施例１と同様にして表面保護フィルム用基材（厚み１５μｍ）を得た。得られた表面保護フィルム用基材のＲ０（５５０）は１１．２ｎｍであり、Ｒｔｈ（５５０）は１７．８ｎｍであり、Ｒ４５（５５０）は１１．９ｎｍであり、［Ｒ４５（５５０）－Ｒ０（５５０）］は０．７ｎｍであった。得られた表面保護フィルム用基材を上記（２）～（４）の評価に供した。結果を表１に示す。 <Example 2>
A substrate for a surface protective film (thickness: 15 μm) was obtained in the same manner as in Example 1 except that the extrusion amount of the extruder and the speed of the cast roll were adjusted. R0 (550) of the obtained base material for surface protective film was 11.2 nm, Rth (550) was 17.8 nm, R45 (550) was 11.9 nm, and [R45 (550) -R0 (550)] was 0.7 nm. The obtained substrate for a surface protective film was subjected to the above-mentioned evaluations (2) to (4). Table 1 shows the results.
＜実施例３＞
　市販のポリカーボネート樹脂（三菱エンジニアリングプラスチックス（株）製　商品名「ユーピロンＨ－４０００」を１２０℃で５時間真空乾燥をした後、単軸押出機（東芝機械社製、シリンダー温度２５５℃）、Ｔダイ（幅１７００ｍｍ、温度２５５℃）、キャストロール（温度１３０℃）および巻取機を備えたフィルム製膜装置を用いて、厚み４０μｍのフィルムを作製し、表面保護フィルム用基材とした。得られた表面保護フィルム用基材のＲ０（５５０）は２．６ｎｍであり、Ｒｔｈ（５５０）は４３．９ｎｍであり、Ｒ４５（５５０）は１５．１ｎｍであり、［Ｒ４５（５５０）－Ｒ０（５５０）］は１２．５ｎｍであった。得られた表面保護フィルム用基材を上記（２）～（４）の評価に供した。結果を表１に示す。 <Example 3>
Commercially available polycarbonate resin (trade name “Iupilon H-4000” manufactured by Mitsubishi Engineering-Plastics Corporation) was vacuum-dried at 120 ° C. for 5 hours, and then a single-screw extruder (manufactured by Toshiba Machine Co., cylinder temperature 255 ° C.), T Using a film forming apparatus equipped with a die (width 1700 mm, temperature 255 ° C.), cast roll (temperature 130 ° C.) and a winder, a film having a thickness of 40 μm was prepared and used as a substrate for a surface protective film. R0 (550) of the obtained base material for surface protective film was 2.6 nm, Rth (550) was 43.9 nm, R45 (550) was 15.1 nm, and [R45 (550) −R0 ( 550)] was 12.5 nm The obtained substrate for a surface protective film was subjected to the evaluations of the above (2) to (4), and the results are shown in Table 1.
＜実施例４＞
　下記の原料を用いてポリマーアロイフィルムを作製した。
使用原料
ＦＤＰＭ：９，９－ビス（２－メトキシカルボニルエチル）フルオレン［９，９－ビス（２－カルボキシエチル）フルオレン（またはフルオレン－９，９－ジプロピオン酸）のジメチルエステル］、特開２００５－８９４２２号公報の実施例１記載のアクリル酸ｔ－ブチルをアクリル酸メチル［３７．９ｇ（０．４４モル）］に変更したこと以外は同様にして合成したもの
ＢＰＥＦ：９，９－ビス［４－（２－ヒドロキシエトキシ）フェニル］フルオレン、大阪ガスケミカル（株）製
ＥＧ：エチレングリコール
ＰＣ：ビスフェノールＡ型ポリカ－ボネート樹脂、三菱エンジニアリングプラスチックス（株）製「ユーピロンＨ－４０００」 <Example 4>
A polymer alloy film was prepared using the following raw materials.
Raw material used: FDPM: 9,9-bis (2-methoxycarbonylethyl) fluorene [dimethyl ester of 9,9-bis (2-carboxyethyl) fluorene (or fluorene-9,9-dipropionic acid)], JP-A-2005 BPEF: 9,9-bis [synthesized in the same manner except that t-butyl acrylate described in Example 1 of JP-A-89422 was changed to methyl acrylate [37.9 g (0.44 mol)]. 4- (2-hydroxyethoxy) phenyl] fluorene, EG manufactured by Osaka Gas Chemical Co., Ltd .: ethylene glycol PC: bisphenol A type polycarbonate resin, "Iupilon H-4000" manufactured by Mitsubishi Engineering-Plastics Corporation.
　ＦＤＰＭ　１．００モル、ＢＰＥＦ　０．８０モル、ＥＧ　２．２０モルに、エステル交換触媒として酢酸マンガン・４水和物２×１０－４モルおよび酢酸カルシウム・１水和物８×１０－４モルを加え、撹拌しながら徐々に加熱溶融した。２３０℃まで昇温した後、トリメチルホスフェート１４×１０－４モル、酸化ゲルマニウム２０×１０－４モルを加え、２７０℃、０．１３ｋＰａ以下に到達するまで、徐々に昇温、減圧しながらＥＧを除去した。所定の撹拌トルクに到達後、内容物を反応器から取り出し、フルオレン環含有ポリエステルのペレットを調製した。得られたペレットを１Ｈ－ＮＭＲにより分析したところ、フルオレン環含有ポリエステルに導入されたジカルボン酸成分の１００モル％がＦＤＰＭ由来であり、導入されたジオール成分の８０モル％がＢＰＥＦ由来、２０モル％がＥＧ由来であった。得られたフルオレン環含有ポリエステルのガラス転移温度Ｔｇは１２６℃、重量平均分子量Ｍｗは４３６００であった。得られたフルオレン環含有ポリエステルとＰＣとを２０／８０（重量比）で二軸混練機で混練し、ポリマーアロイのペレットを作製した。 To 1.00 mol of FDPM, 0.80 mol of BPEF, 2.20 mol of EG, 2 × 10 −4 mol of manganese acetate tetrahydrate and 8 × 10 −4 mol of calcium acetate monohydrate as transesterification catalysts Was added, and the mixture was gradually heated and melted with stirring. After the temperature was raised to 230 ° C., 14 × 10 −4 mol of trimethyl phosphate and 20 × 10 −4 mol of germanium oxide were added, and the EG was gradually heated and depressurized until the temperature reached 270 ° C. and 0.13 kPa or less. Removed. After reaching a predetermined stirring torque, the contents were taken out of the reactor, and fluorene ring-containing polyester pellets were prepared. When the obtained pellets were analyzed by 1 H-NMR, 100 mol% of the dicarboxylic acid component introduced into the fluorene ring-containing polyester was derived from FDPM, and 80 mol% of the introduced diol component was derived from BPEF, and 20 mol%. % Were from EG. The glass transition temperature Tg of the obtained fluorene ring-containing polyester was 126 ° C., and the weight average molecular weight Mw was 43,600. The obtained fluorene ring-containing polyester and PC were kneaded at 20/80 (weight ratio) with a biaxial kneader to prepare polymer alloy pellets.
　得られたポリマーアロイのペレットを８０℃で５時間真空乾燥をした後、単軸押出機（東芝機械社製　シリンダー温度２５５℃）、Ｔダイ（幅１７００ｍｍ、温度２５５℃）、キャストロール（温度１２５℃）および巻取機を備えたフィルム製膜装置を用いて、厚み１６０μｍのポリマーアロイフィルムを作製した。このフィルムを、長さ方向および幅方向にそれぞれ２倍に同時二軸延伸した。延伸温度は１７０℃、延伸速度は長さ方向および幅方向ともに１．４％／秒であった。このようにして、表面保護フィルム用基材（厚み４０μｍ）を得た。得られた表面保護フィルム用基材のＲ０（５５０）は２０ｎｍであり、Ｒｔｈ（５５０）は８５ｎｍであり、Ｒ４５（５５０）は２８．１ｎｍであり、［Ｒ４５（５５０）－Ｒ０（５５０）］は８．１ｎｍであった。得られた表面保護フィルム用基材を上記（２）～（４）の評価に供した。結果を表１に示す。 After vacuum-drying the obtained polymer alloy pellets at 80 ° C. for 5 hours, a single screw extruder (cylinder temperature 255 ° C., manufactured by Toshiba Machine Co., Ltd.), a T-die (width 1700 mm, temperature 255 ° C.), cast roll (temperature 125 C) and a film forming apparatus equipped with a winder to produce a polymer alloy film having a thickness of 160 μm. This film was simultaneously biaxially stretched twice in the length and width directions. The stretching temperature was 170 ° C., and the stretching speed was 1.4% / sec in both the length and width directions. Thus, a substrate for a surface protective film (thickness: 40 μm) was obtained. R0 (550) of the obtained base material for surface protective film was 20 nm, Rth (550) was 85 nm, R45 (550) was 28.1 nm, and [R45 (550) -R0 (550)]. Was 8.1 nm. The obtained substrate for a surface protective film was subjected to the above-mentioned evaluations (2) to (4). Table 1 shows the results.
＜実施例５＞
　市販のトリアセチルセルロース（ＴＡＣ）フィルム（富士フイルム社製、製品名「ＴＤ８０ＵＬ」）をそのまま用いて表面保護フィルム用基材（厚み８０μｍ）とした。表面保護フィルム用基材のＲ０（５５０）は４．９ｎｍであり、Ｒｔｈ（５５０）は５２．６ｎｍであり、Ｒ４５（５５０）は８．７ｎｍであり、［Ｒ４５（５５０）－Ｒ０（５５０）］は３．８ｎｍであった。表面保護フィルム用基材を上記（２）～（４）の評価に供した。結果を表１に示す。 <Example 5>
A commercially available triacetyl cellulose (TAC) film (manufactured by FUJIFILM Corporation, product name "TD80UL") was used as it was to prepare a substrate for a surface protection film (thickness: 80 m). R0 (550) of the substrate for a surface protective film is 4.9 nm, Rth (550) is 52.6 nm, R45 (550) is 8.7 nm, and [R45 (550) -R0 (550). ] Was 3.8 nm. The substrate for a surface protective film was subjected to the evaluations (2) to (4) above. Table 1 shows the results.
＜実施例６＞
　市販のシクロオレフィン系樹脂フィルム（日本ゼオン社製、製品名「ＺＦ１４」）を用いたこと以外は実施例１と同様にして表面保護フィルム用基材（厚み４０μｍ）を得た。得られた表面保護フィルム用基材のＲ０（５５０）は２．０ｎｍであり、Ｒｔｈ（５５０）は７．９ｎｍであり、Ｒ４５（５５０）は２．７ｎｍであり、［Ｒ４５（５５０）－Ｒ０（５５０）］は０．７ｎｍであった。得られた表面保護フィルム用基材を上記（２）～（４）の評価に供した。結果を表１に示す。 <Example 6>
A substrate for a surface protection film (thickness: 40 μm) was obtained in the same manner as in Example 1 except that a commercially available cycloolefin-based resin film (manufactured by Zeon Corporation, product name “ZF14”) was used. R0 (550) of the obtained base material for surface protective film was 2.0 nm, Rth (550) was 7.9 nm, R45 (550) was 2.7 nm, and [R45 (550) -R0 (550)] was 0.7 nm. The obtained substrate for a surface protective film was subjected to the above-mentioned evaluations (2) to (4). Table 1 shows the results.
＜実施例７＞
　市販のアクリル樹脂（奇美実業社製、商品名「ＣＭ－２０５」）を１００℃で５時間真空乾燥をした後、単軸押出機（東芝機械社製、シリンダー温度２３０℃）、Ｔダイ（幅１７００ｍｍ、温度２３０℃）、キャストロール（温度１００℃）および巻取機を備えたフィルム製膜装置を用いて、厚み１６０μｍのフィルムを作製した。このフィルムを、長さ方向および幅方向にそれぞれ２倍に同時二軸延伸した。延伸温度は１４６℃、延伸速度は長さ方向および幅方向ともに７．１％／秒であった。このようにして、表面保護フィルム用基材（厚み４０μｍ）を得た。得られた表面保護フィルム用基材のＲ０（５５０）は０．５ｎｍであり、Ｒｔｈ（５５０）は－３９ｎｍであり、Ｒ４５（５５０）は１０．１ｎｍであり、［Ｒ４５（５５０）－Ｒ０（５５０）］は９．６ｎｍであった。得られた表面保護フィルム用基材を上記（２）～（４）の評価に供した。結果を表１に示す。 <Example 7>
After vacuum drying a commercially available acrylic resin (trade name “CM-205”, manufactured by Kimei Industry Co., Ltd.) at 100 ° C. for 5 hours, a single screw extruder (manufactured by Toshiba Machine Co., cylinder temperature 230 ° C.), T-die (width) A film having a thickness of 160 μm was produced using a film forming apparatus equipped with a cast roll (temperature 1100 mm, temperature 230 ° C.), a cast roll (temperature 100 ° C.) and a winder. This film was simultaneously biaxially stretched twice in the length and width directions. The stretching temperature was 146 ° C., and the stretching speed was 7.1% / sec in both the length and width directions. Thus, a substrate for a surface protective film (thickness: 40 μm) was obtained. R0 (550) of the obtained substrate for surface protective film was 0.5 nm, Rth (550) was −39 nm, R45 (550) was 10.1 nm, and [R45 (550) −R0 ( 550)] was 9.6 nm. The obtained substrate for a surface protective film was subjected to the above-mentioned evaluations (2) to (4). Table 1 shows the results.
＜比較例１＞
　延伸温度を１６７℃としたこと以外は実施例４と同様にして表面保護フィルム用基材（厚み４０μｍ）を得た。得られた表面保護フィルム用基材のＲ０（５５０）は３２ｎｍであり、Ｒｔｈ（５５０）は９１ｎｍであり、Ｒ４５（５５０）は４５．１ｎｍであり、［Ｒ４５（５５０）－Ｒ０（５５０）］は１３．１ｎｍであった。得られた表面保護フィルム用基材を上記（２）～（４）の評価に供した。結果を表１に示す。 <Comparative Example 1>
A substrate for a surface protective film (40 μm in thickness) was obtained in the same manner as in Example 4 except that the stretching temperature was 167 ° C. R0 (550) of the obtained base material for surface protective film is 32 nm, Rth (550) is 91 nm, R45 (550) is 45.1 nm, and [R45 (550) -R0 (550)]. Was 13.1 nm. The obtained substrate for a surface protective film was subjected to the above-mentioned evaluations (2) to (4). Table 1 shows the results.
＜比較例２＞
　厚みを８０μｍにしたこと以外は実施例３と同様にして表面保護フィルム用基材（厚み８０μｍ）を得た。得られた表面保護フィルム用基材のＲ０（５５０）は５．６ｎｍであり、Ｒｔｈ（５５０）は１０２．６ｎｍであり、Ｒ４５（５５０）は１９．４ｎｍであり、［Ｒ４５（５５０）－Ｒ０（５５０）］は１３．８ｎｍであった。得られた表面保護フィルム用基材を上記（２）～（４）の評価に供した。結果を表１に示す。 <Comparative Example 2>
A substrate for a surface protection film (thickness: 80 μm) was obtained in the same manner as in Example 3 except that the thickness was changed to 80 μm. R0 (550) of the obtained base material for surface protective film is 5.6 nm, Rth (550) is 102.6 nm, R45 (550) is 19.4 nm, and [R45 (550) -R0 (550)] was 13.8 nm. The obtained substrate for a surface protective film was subjected to the above-mentioned evaluations (2) to (4). Table 1 shows the results.
＜比較例３＞
　市販の超高位相差ポリエチレンテレフタレートフィルム（三菱ケミカル社製、商品名「ダイアホイルＭＲＦ３８ＣＫ」）をそのまま用いて表面保護フィルム用基材（厚み３８μｍ）とした。表面保護フィルム用基材のＲ０（５５０）は２９５０ｎｍであり、Ｒｔｈ（５５０）は８９８９．４ｎｍであり、Ｒ４５（５５０）は３４４５．５ｎｍであり、［Ｒ４５（５５０）－Ｒ０（５５０）］は４９５．５ｎｍであった。表面保護フィルム用基材を上記（２）～（４）の評価に供した。結果を表１に示す。 <Comparative Example 3>
A commercially available ultra-high retardation polyethylene terephthalate film (trade name “Diafoil MRF38CK” manufactured by Mitsubishi Chemical Corporation) was used as it was to prepare a substrate for a surface protection film (thickness: 38 μm). R0 (550) of the substrate for surface protective film is 2950 nm, Rth (550) is 8899.4 nm, R45 (550) is 3445.5 nm, and [R45 (550) -R0 (550)] is It was 495.5 nm. The substrate for a surface protective film was subjected to the evaluations (2) to (4) above. Table 1 shows the results.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
＜評価＞
　表１から明らかなように、本発明の実施例の表面保護フィルム用基材は、虹ムラが防止され、全光線透過率に優れ、かつ、端部の光漏れが抑制されていることがわかる。なお、着色についても虹ムラおよび光漏れと同様の結果が得られることを確認した。 <Evaluation>
As is clear from Table 1, it can be seen that the substrate for a surface protective film of the example of the present invention prevents rainbow unevenness, has excellent total light transmittance, and suppresses light leakage at the end. . In addition, it was confirmed that the same result as that of rainbow unevenness and light leakage was obtained for coloring.
　本発明の表面保護フィルム用基材は、表面保護フィルムに好適に用いられる。本発明の表面保護フィルムは、光学フィルム（最終的には、画像表示装置）が実際に使用されるまでの間、当該光学フィルムを保護するために用いられる。本発明の表面保護フィルム用基材および表面保護フィルムを用いることにより、画像表示装置の光学検査の精度を顕著に向上させることができる。
 
  The substrate for a surface protective film of the present invention is suitably used for a surface protective film. The surface protective film of the present invention is used to protect the optical film until the optical film (finally, the image display device) is actually used. By using the surface protective film substrate and the surface protective film of the present invention, the precision of the optical inspection of the image display device can be significantly improved.

Claims (7)

  1. 　正面方向の位相差Ｒ０（５５０）と極角４５°および方位角４５°方向の位相差Ｒ４５（５５０）とが下記の関係を満足する、表面保護フィルム用基材：
    　　　Ｒ４５（５５０）－Ｒ０（５５０）≦１３（ｎｍ）。     A base material for a surface protective film, wherein the phase difference R0 (550) in the front direction and the phase difference R45 (550) in the polar angle of 45 ° and the azimuth angle of 45 ° satisfy the following relationship:
    R45 (550) -R0 (550) ≤13 (nm).
  2. 　前記正面方向の位相差Ｒ０（５５０）が２０ｎｍ以下である、請求項１に記載の表面保護フィルム用基材。 The base material for a surface protective film according to claim 1, wherein the retardation R0 (550) in the front direction is 20 nm or less.
  3. 　全光線透過率が８０％以上であり、ヘイズが１．０％以下である、請求項１または２に記載の表面保護フィルム用基材。 The substrate for a surface protective film according to claim 1 or 2, wherein the total light transmittance is 80% or more and the haze is 1.0% or less.
  4. 　前記表面保護フィルム用基材が、ポリカーボネート、ポリエステル、シクロオレフィン系樹脂、アクリル系樹脂およびセルロース樹脂から選択される少なくとも1つの樹脂を含む、請求項１から３のいずれかに記載の表面保護フィルム用基材。 The surface protection film according to any one of claims 1 to 3, wherein the surface protection film substrate includes at least one resin selected from polycarbonate, polyester, cycloolefin-based resin, acrylic resin, and cellulose resin. Base material.
  5. 　前記表面保護フィルム用基材が、脂環式構造または負の固有複屈折を示す芳香族環構造を有する樹脂を含む、請求項４に記載の表面保護フィルム用基材。 The substrate for a surface protective film according to claim 4, wherein the substrate for a surface protective film includes a resin having an alicyclic structure or an aromatic ring structure exhibiting negative intrinsic birefringence.
  6. 　請求項１から５のいずれかに記載の表面保護フィルム用基材と粘着剤層とを含む、表面保護フィルム。 A surface protective film comprising the substrate for a surface protective film according to claim 1 and a pressure-sensitive adhesive layer.
  7. 　光学フィルムと、該光学フィルムに剥離可能に貼り合わせられた請求項６に記載の表面保護フィルムと、を含む、表面保護フィルム付光学フィルム。
          An optical film with a surface protective film, comprising: an optical film; and the surface protective film according to claim 6, which is releasably attached to the optical film.
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